Wireless solar power delivery

ABSTRACT

Example implementations relate to a solar panel system including solar cells and an inverter configured to receive electrical energy generated by solar cells and to convert the electrical energy to an electrical signal having an oscillation frequency. The system also include a transmit resonator coupled to the inverter and configured to resonate at the oscillation frequency. Moreover, the transmit resonator may be coupled via a wireless resonant coupling link to a receive resonator that is also configured to resonate at the oscillation frequency. Further, the system may also include a controller configured to determine for the system a mode of operation from among the following modes: (i) a common mode, (ii) a differential mode, and (iii) an inductive mode. And the controller is then configured to instruct the transmit resonator to provide via the wireless resonant coupling link electrical power according to the determined mode of operation.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

Electronic devices, such as mobile phones, laptops, and tablets, havebecome an integral part of daily life. Other machines, such as cars,which have conventionally used non-electric power sources, areincreasingly relying on electricity as a power source. As electronicdevices are often mobile, it may not be feasible for devices to stayconnected to a power source via wires. Thus, electronic devices may usebatteries to supply electric power when a device is not coupled to afixed power source.

Current battery technology, however, often does not meet the chargecapacity and/or discharge rate demands of electronic devices, which maylimit the range of moveable devices. Even in cases where batteries meetthe power demands of a given device, such a device usually must becoupled to a fixed charging source via wires in order to recharge itsbattery. Such wired charging mechanisms may limit the movement, and thusthe usability, of the device while it is being charged. Also, as thenumber of devices connected to a charging source increases, the numberof wires in the proximity of an electrical outlet may increase, causing“cord clutter.”

SUMMARY

Example implementations may relate to systems for wirelesslytransmitting power that is harnessed from solar energy. These systemsmay take the form of a solar panel system that includes solar cells thatconvert solar energy to electrical energy as well as various componentsthat are configured to use this electrical energy to wirelessly provideelectrical power. Alternatively, these systems may take the form of awireless power transmission system that can connect to external solarpanel systems and also includes components configured to receiveelectrical energy generated by these external solar panel systems and tothen to use this electrical energy to wirelessly provide electricalpower.

In one aspect, a solar panel system is provided. The solar panel systemincludes one or more solar cells configured to convert solar energy toelectrical energy. The solar panel system also includes at least oneinverter coupled to the one or more solar cells and configured to (i)receive the electrical energy and (ii) convert the electrical energy toan electrical signal having an oscillation frequency. The solar panelsystem additionally includes at least one transmit resonator coupled tothe at least one inverter, where the at least one transmit resonator isconfigured to resonate at at least the oscillation frequency, and wherethe at least one transmit resonator is operable to be coupled via atleast one wireless resonant coupling link to at least one receiveresonator that is also configured to resonate at at least theoscillation frequency. The solar panel system further includes acontroller configured to perform operations. The operations includedetermining for the solar panel system at least one mode of operationfrom among one or more of the following modes: (i) a common mode, (ii) adifferential mode, and (iii) an inductive mode. The operations alsoinclude instructing the at least one transmit resonator to provide viathe at least one wireless resonant coupling link electrical poweraccording to the determined at least one mode of operation.

In another aspect, a wireless power transmission system is provided. Thewireless power transmission system includes at least one transmitresonator operable to receive at least one electrical signal having anoscillation frequency, where the at least one electrical signal isgenerated from electrical energy that the wireless power transmissionsystem receives from one or more solar panel system, where the one ormore solar panel systems are configured to convert solar energy toelectrical energy, where the at least one transmit resonator isconfigured to resonate at at least the oscillation frequency, and wherethe at least one transmit resonator is operable to be coupled via atleast one wireless resonant coupling link to at least one receiveresonator that is also configured to resonate at at least theoscillation frequency. The wireless power transmission system alsoincludes a controller configured to perform operations. The operationsinclude determining for the wireless power transmission system at leastone mode of operation from among one or more of the following modes: (i)a common mode, (ii) a differential mode, and (iii) an inductive mode.The operations also include instructing the at least one transmitresonator to provide via the at least one wireless resonant couplinglink electrical power according to the determined at least one mode ofoperation.

In yet another aspect, a method is provided. The method involvesdetermining, by a controller, for a wireless power transmission systemat least one mode of operation from among one or more of the followingmodes: (i) a common mode, (ii) a differential mode, and (iii) aninductive mode, where the wireless power transmission system includes atleast one transmit resonator operable to receive at least one electricalsignal having an oscillation frequency, where the at least oneelectrical signal is generated from electrical energy that the wirelesspower transmission system receives from one or more solar panel system,where the one or more solar panel systems are configured to convertsolar energy to electrical energy, where the at least one transmitresonator is configured to resonate at at least the oscillationfrequency, and where the at least one transmit resonator is operable tobe coupled via at least one wireless resonant coupling link to at leastone receive resonator that is also configured to resonate at at leastthe oscillation frequency. The method also involves instructing, by thecontroller, the at least one transmit resonator to provide via the atleast one wireless resonant coupling link electrical power according tothe determined at least one mode of operation.

In yet another aspect, a system is provided. The system may includemeans for determining for the system at least one mode of operation fromamong one or more of the following modes: (i) a common mode, (ii) adifferential mode, and (iii) an inductive mode, where the systemincludes at least one transmit resonator operable to receive at leastone electrical signal having an oscillation frequency, where the atleast one electrical signal is generated from electrical energy that thewireless power transmission system receives from one or more solar panelsystem, where the one or more solar panel systems are configured toconvert solar energy to electrical energy, where the at least onetransmit resonator is configured to resonate at at least the oscillationfrequency, and where the at least one transmit resonator is operable tobe coupled via at least one wireless resonant coupling link to at leastone receive resonator that is also configured to resonate at at leastthe oscillation frequency. The system may also include means forinstructing the at least one transmit resonator to provide via the atleast one wireless resonant coupling link electrical power according tothe determined at least one mode of operation.

These as well as other aspects, advantages, and alternatives will becomeapparent to those of ordinary skill in the art by reading the followingdetailed description, with reference where appropriate to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram illustrating the components of awireless power delivery system, according to an example embodiment.

FIG. 2 is a functional block diagram illustrating an impedance matchingcircuit coupled to a transmitter, according to an example embodiment.

FIG. 3 is a diagram illustrating a representation of a bidirectionalcoupler used in a mathematical derivation, according to an exampleembodiment.

FIGS. 4A to 4B illustrate simplified circuit diagram illustratinginductive resonant coupling, according to an example embodiment.

FIGS. 5A to 5C illustrate a simplified circuit diagram illustratingcommon mode capacitive resonant coupling, according to an exampleembodiment.

FIGS. 6A to 6B illustrate a simplified circuit diagram illustratingdifferential mode capacitive resonant coupling, according to an exampleembodiment.

FIG. 7 illustrates a method of delivering electrical power from atransmitter to one or more loads, according to an example embodiment.

FIG. 8 is a table illustrating modes of operation of a system, accordingto an example embodiment.

FIGS. 9A to 9B illustrate a TDMA wireless resonant coupling channel,according to an example embodiment.

FIG. 10 is a functional block diagram illustrating a wireless powerdelivery system employing side-channel communications, according to anexample embodiment.

FIG. 11 illustrates a method for confirming that a power transfer linkand a side-channel communication link are established with the samereceiver, according to an example embodiment.

FIG. 12 is a functional block diagram illustrating a wireless powerdelivery system employing multiplexed power transfer, according to anexample embodiment.

FIG. 13 illustrates a phase shift of a chain of repeaters repeating atransmitter near field, according to an example embodiment.

FIG. 14 illustrates a method of controlling the phase shift of nearfields in a system, according to an example embodiment.

FIG. 15 illustrates an implementation of a wireless power deliverysystem according to an example embodiment.

FIG. 16 is a flowchart illustrating a method of using a high-frequencytest pulse to determine one or more properties of reflecting entities ina near-field region of an oscillating field of a transmitter, accordingto an example embodiment.

FIG. 17 illustrates a configuration of a solar panel system, accordingto an example embodiment.

FIG. 18 illustrates a first example distribution of power among variousloads in an arrangement including at least one solar panel system,according to an example embodiment.

FIG. 19 illustrates the first example distribution of power in a houseincluding at least one solar panel system, according to an exampleembodiment.

FIG. 20 illustrates a second example distribution of power among variousloads in an arrangement including at least one solar panel system,according to an example embodiment.

FIG. 21 illustrates the second example distribution of power in a houseincluding at least one solar panel system, according to an exampleembodiment.

FIG. 22 illustrates a configuration of a wireless power transmissionsystem, according to an example embodiment.

FIG. 23 illustrates a first example distribution of power among variousloads in an arrangement including at least one wireless powertransmission system, according to an example embodiment.

FIG. 24 illustrates the first example distribution of power in a houseincluding at least one wireless power transmission system, according toan example embodiment.

FIG. 25 illustrates a second example distribution of power among variousloads in an arrangement including at least one wireless powertransmission system, according to an example embodiment.

FIG. 26 illustrates the second example distribution of power in a houseincluding at least one wireless power transmission system, according toan example embodiment.

DETAILED DESCRIPTION

Exemplary methods and systems are described herein. It should beunderstood that the word “exemplary” is used herein to mean “serving asan example, instance, or illustration.” Any embodiment or featuredescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other embodiments or features. Theexemplary embodiments described herein are not meant to be limiting. Itwill be readily understood that certain aspects of the disclosed systemsand methods can be arranged and combined in a wide variety of differentconfigurations, all of which are contemplated herein.

Furthermore, the particular arrangements shown in the Figures should notbe viewed as limiting. It should be understood that other embodimentsmay include more or less of each element shown in a given Figure.Further, some of the illustrated elements may be combined or omitted.Yet further, an exemplary embodiment may include elements that are notillustrated in the Figures.

Furthermore, the term “capacitor” as used herein should be understoodbroadly as any system, including one or more elements, with a capacitiveproperty. As such, the term “capacitor” may be used to refer to a lumpedcapacitive element and/or to a distributed capacitive element.Similarly, the term “inductor” as used herein should be understoodbroadly as any system, including one or more elements, with an inductiveproperty. As such, the term “inductor” may be used to refer to a lumpedinductive element and/or to a distributed inductive element.

I. Overview

Wireless power transfer involves the transmission of electrical powerfrom a power source to a receiver without coupling the receiver to thepower source with solid conductors (e.g., wires). Some conventionalwireless power delivery systems may include a transmitter and a receiverthat are inductively coupled via an oscillating magnetic field. Forinstance, a power signal from a power source may be delivered to atransmit-coil in a transmitter to create an oscillating magnetic field.This oscillating magnetic field passes through a receive-coil in areceiver and induces AC to flow in the receiver and to a load. Themagnitude of coupling between the transmitter and the receiver can berepresented by a coupling factor k, a dimensionless parameterrepresenting the fraction of flux coupling the transmitter and thereceiver. In order to establish efficient power transfer in suchconventional systems, the coupling factor k must be maintained at asufficiently high level. Accordingly, the receiver coil usually needs tobe located in close proximity to, and precisely positioned relative to,the transmitter coil. In addition, large transmitter and receiver coilsmay be necessary in order to ensure sufficient coupling and to achievereasonably efficient power transfer.

Systems, devices, and methods disclosed herein relate to wireless powerdelivery systems that utilize resonant coupling to transfer powerefficiently from a transmitter to a receiver. Such systems and methodsmay have less stringent proximity and/or positional requirements ascompared to conventional inductively-coupled wireless power systems.That is, systems and methods disclosed herein may provide efficientwireless power transfer even when the coupling factor k is small.Specifically, in accordance with example embodiments, power may betransferred between a resonantly-coupled transmitter and receiver via anoscillating field generated by the transmitter. The oscillating fieldmay include an oscillating magnetic field component and/or anoscillating electric field component.

In example systems, the transmitter may include a transmit-resonator andthe receiver may include a receive-resonator. A resonator, such as thetransmit-resonator or the receive-resonator can be characterized by oneor more resonant frequencies, among other factors. In particular, atransmit-resonator and a corresponding receive-resonator may beconfigured to resonate at a common resonant frequency. When resonating,the receive-resonator may produce an output signal oscillating at theresonant frequency. The output signal may then be rectified or otherwiseconverted to electrical power, which can be delivered to a load.

An oscillating electric and/or magnetic field may be described by itsresonant frequency, ω₀. Such fields have a resonant wavelength

${\lambda_{0} = \frac{2\;\pi\; c}{\omega_{0}}},$where c is the speed of light in the medium through which the field istransmitted. The region within approximately one resonant wavelengthfrom the resonator may be termed the “near field.” The electric and/ormagnetic field in the near field is predominantly non-radiative.Optionally, the near field may be considered the field that is at orbelow distances shorter than the 3*λ, where λ is a wavelength of thetransmitted signal. Further, a field strength of the near field decaysvery rapidly with distance. The region beyond approximately one or a fewresonant wavelengths from the resonator is known as the “far field.” Thefar field is almost exclusively radiative (e.g., RF radiation), and canbe described as the region beyond the 3*λ distance.

A resonator, such as the transmit-resonator and the receive-resonator,may be characterized in terms of an intrinsic loss rate

, which is a metric of energy dissipated over resonant cycles. The ratio

$Q = \frac{\omega_{0}}{2\Gamma}$defines a quality factor for the resonator expressed in terms of energyloss per cycle. A resonator that dissipates a smaller amount of energyper cycle generally has a higher quality factor Q. A system with a highquality factor Q (e.g., above 100) may be considered to be highlyresonant.

Resonant systems with high-Q resonators may be operable to transferpower with high efficiency, even in situations where there may be weakcoupling between the transmit-resonator and receive-resonator. That is,systems with a low coupling factor k (e.g., k=0.1) may still transferpower with high efficiency by employing resonators with sufficientlyhigh quality factor Q (e.g., Q>100), because the power transferefficiency is a function of the quality factor Q and the coupling factork. Accordingly, highly resonant systems may be operable to wirelesslytransfer power over a long range. Furthermore, in some embodiments,resonant systems may achieve greater efficiencies than systems employingwired power transfer.

As described above, to transfer power, transmit-resonators andreceive-resonators may be coupled via an oscillating magnetic fieldand/or an oscillating electric field. Accordingly, example embodimentsmay be operable using any one or more of three coupling modes at anygiven time: (i) inductive mode, (ii) differential capacitive mode, and(iii) common capacitive mode.

In inductive mode, at least one inductor of the transmit-resonatorreceives a signal from the power source and resonates to generate amagnetic field that oscillates at a resonant frequency ω₀. In such ascenario, at least one inductor of the receive-resonator may oscillatein response to being in proximity to the magnetic field. In differentialcapacitive mode, each capacitor of the transmit-resonator and thereceive-resonator develops capacitance between two conductors. In commoncapacitive mode, each capacitor of the transmit-resonator and thereceive-resonator develops a capacitance between a first conductor and aground or common conductor. In common capacitive mode, the ground orcommon conductor may include an earth connection. In other words, theground or common conductor may include an electrical connection to theearth's potential. The electrical connection may be a physicalconnection (e.g., using a metal stake), or may be a capacitiveconnection to the earth's potential. The transmitter may include acontroller to determine whether and when to deliver power via inductivemode, differential capacitive mode, and/or common capacitive mode and tocontrol various elements of the transmitter accordingly.

In resonant wireless power transfer, higher efficiencies may be achievedby dynamically adjusting impedances (resistance and/or reactance) on thetransmitting side and/or the receiving side. For instance, thetransmitter may include an impedance matching network coupled to thetransmit-resonator. The impedance matching network on the transmittingside may be controlled so as to continually or intermittently adjust theimpedance of the transmitter and associated elements. Similarly, thereceiver may include an impedance matching network coupled to thereceive-resonator. The impedance matching network on the receiving sidemay be controlled so as to continually or intermittently adjust theimpedance of the receiver and associated elements.

In an example embodiment, the controller may carry out operations tocreate a circuit model based on a transmit-receive circuit associatedwith the transmitter and the receiver. Using this transmit-receivecircuit, the coupling factor k can also be calculated. Because theimpedance associated with the receiver can be calculated from thereflected power received via the bidirectional RF coupler, the onlyremaining unknown in the circuit model is the coupling factor k for thetransmitter and the receiver. The circuit model determines a specificrelationship between the coupling factor k and the impedance of thereceiver. By determining the coupling coefficient k, an optimallyefficient condition for the power transfer may be calculated orotherwise determined. The impedance(s) on the transmitting and/orreceiving sides can be adjusted via the respective impedance matchingnetworks so as to achieve and/or maintain the optimally efficientcondition. In particular, dynamic impedance adjustment may be employedas the coupling between the transmit-resonator and the receive-resonatorchanges when the orientation and spatial relationship between thereceiver and the transmitter changes.

In some wireless power delivery systems described herein, thetransmitter may be operable to transfer power to any of a plurality ofreceivers. As many devices may be positioned within range of thetransmitter for wireless power transfer, the transmitter may beconfigured to distinguish legitimate receivers from illegitimate devicesthat are not intended recipients of power transfer. These illegitimatedevices may otherwise act as parasitic loads by receiving power from thetransmitter without permission. Thus, prior to transferring power to arespective receiver, the transmitter may carry out an authenticationprocess to authenticate the receiver. The authentication process may beconducted, at least in part, over a wireless side-channel communicationlink that establishes a secondary channel between the transmitter andthe receiver, separate from the resonant power link. Alternatively oradditionally, the transmitter may employ time-division and/orfrequency-division multiplexing to transfer power to a plurality oflegitimate receivers respectively.

In accordance with example embodiments, the resonant wireless powerdelivery system may include one or more resonant repeaters configured tospatially extend the near-field region of the oscillating field. Suchresonant repeaters may be passive, in the sense that they may be poweredonly by the near field in which they are positioned. A plurality ofrepeaters may be configured in a chain-like configuration (e.g., a“daisy-chain”), to extend the transmitter near field, such that eachsubsequent repeater in the chain resonantly repeats the near field of anearlier link in the resonant repeater chain. The spacing betweenrepeaters and/or between a transmitter and a repeater may be limited bydecay of the near field from one repeater to the next. Furthermore, amaximum distance to which the transmitter near field may be extended maybe limited due to an accumulated phase shift across chained repeaters.

In accordance with example embodiments, both the maximum repeaterspacing limitation and the accumulated phase shift limitations may beovercome by including additional capabilities in the repeaters. First,by using active repeaters that each include an independent power source,the active repeaters can “inject” additional power into the repeatedfields, and thereby mitigate decay of the near field that may otherwiseoccur. Second, cumulative phase delay across a chain or array ofrepeaters may be suppressed or eliminated by including one or more phaseadjustment elements in some or all of the repeaters. Additionally oralternatively, phase control may be introduced in repeaters by means ofmetamaterials. Furthermore, phase control of repeaters may beimplemented such that the transmitter and active repeaters behavetogether as a collective metamaterial.

In accordance with example embodiments, a wireless power delivery systemmay utilize test signals to probe physical properties of systemcomponents and/or wireless power transmission paths between systemcomponents. More particularly, a transmitter may include a signalgenerator, or the like, configured to transmit or broadcast one or moretypes of wireless signals across the region in which wireless powertransfer may occur. Such signals may be reflected by one or morereflecting entities (e.g., receivers, repeaters, etc.), and theirreflection may then be received by a test-signal receiver of thetransmitter. By analyzing phase and amplitude information of transmittedsignals and their reflections, the transmitter may thus determineelectrical properties of a reflecting entity, as well as of thetransmission path between the transmitter and the reflecting entity.Utilization of the test signal in such a manner may provide diagnosticcapabilities similar to that of a vector network analyzer (VNA), asapplied to a wireless power delivery system.

In an example system, test signals can span a broad frequency range toprovide a frequency sweep, in a manner like that of a VNA frequencysweep. Analysis of such a frequency sweep may then be performed todetermine an impedance of one or more receivers, a number of repeatersbetween the transmitter and a given receiver, a relative location of thetransmitter and the given receiver, and a characteristic impedance of awireless transmission path, among other properties of the system. Thisinformation can be used, in turn, to enhance the accuracy of powerdelivery, and to distinguish between legitimate receivers and possibleunauthorized receivers and/or parasitic devices. In other instances,test signals can be generated as pulses or chirps, being more narrowbandin frequency and or time. Analysis of reflections of such pulse signalsmay then be used in ranging applications, for example.

In accordance with example embodiments, a system for resonant wirelesspower delivery may also wirelessly transmit power that is harnessed fromsolar energy. In particular, example embodiments may relate to or takethe form of a solar panel system. Such a solar panel system may be astand-alone system that is capable of harnessing the sun's rays and thenwirelessly transmitting generated electricity to a receiver. In thisway, an individual may simply position this solar panel system at adesired exterior location (e.g., a roof or a window) and arrange awireless power receiver (perhaps at an interior location) to receive anddistribute power that is generated by the solar panel system.

Alternatively, example embodiments may relate to or take the form of awireless power transmission system. This wireless power transmissionsystem may include at least one transmitter and may be operable toconnect to one or more solar panels, such as to one or more currentlyavailable solar panels for instance. With this wireless powertransmission system, an individual may simply wire these solar panels tothe wireless power transmission system and the wireless powertransmission system may then be set to receive electricity generated bythe solar panels and to then wirelessly provide electrical power usingthe approaches discussed herein. In either case, such systems mayinclude a controller that may determine operating mode(s) for the systemand may cause the transmitter to transmit electrical power in accordancewith these mode(s), such as in accordance with the mode(s) discussedherein.

II. Example Systems and Operations for Wireless Power Delivery

An example system 100 for wireless transfer of power is shown in FIG. 1.The system 100 may include various subsystems, elements, and componentsas described below. One or more subsystems may include a controllerconfigured to carry out one or more of a variety of operations. Inaccordance with example embodiments, a controller may include one ormore processors, memory, and machine language instructions stored in thememory that when executed by the one or more processors cause thecontroller to carry one or more of its controlling functions oroperations. A controller may also include one or more interfaces fordevice control, communications, etc.

In further accordance with example embodiments, various functions andoperations described below may be defined as methods that may be carriedwithin the system, where at least some aspects of the methods can beimplemented based on functions and/or operations carried out by one ormore controllers and/or one or more of processors. Other aspects of themethods may be carried out by other elements or components of thesystem, under control of one or another controller, in response toenvironmental factors, or in response to receiving or detecting asignal, for example.

In an example embodiment, a wireless power delivery system may include apower source configured to wirelessly deliver power to a load via atransmitter and a receiver. As shown in FIG. 1, system 100 may include atransmitter 102 and a receiver 108, both of which may be consideredsubsystems of system 100, and a controller 114. For the sake of brevityin FIG. 1 and elsewhere herein, control functions and operations aregenerally described as being carried out only by the controller 114.Thus, controller 114 may be viewed conceptually as a unified controlfunction. It should be understood, however, that as subsystems of system100, the transmitter 102 and receiver 108 may each include its owncontroller, as described elsewhere herein. Alternatively oradditionally, the controller 114 may include a distributed computingsystem, e.g., a mesh network.

As such, the various control functions and operations attributed tocontroller 114 may be implemented across one or more controllers, suchas ones included (but not shown) in transmitter 102 and receiver 108.For example, an operation described as being carried out by thetransmitter could be done so under control of a controller in thetransmitter. Similarly, an operation described as being carried out bythe receiver could be done so under control of a controller in thereceiver.

In addition to each of the transmitter 102 and receiver 108 possiblyincluding its own controller, each of them may also include and/beconstructed of various types of electrical components. For example,electrical components may include circuit elements such as inverters,varactors, amplifiers, rectifiers, transistors, switches, relays,capacitors, inductors, diodes, transmission lines, resonant cavities,and conductors. Furthermore, the electrical components may be arrangedin any viable electrical configuration, such as lumped or distributed.

Returning to FIG. 100, the transmitter 102 of system 100 may include atransmit-resonator 106. The transmit-resonator 106 may have a high Qvalue and may be configured to resonate at one or more resonantfrequencies. Transmitter 102 may be coupled with power source 104, whichmay be configured to supply transmit-resonator 106 with a signaloscillating at one of the transmit-resonator resonant frequencies. In anexample, the power source 104 may include a power oscillator to generatethe oscillating signal, which may be oscillating at one of thetransmit-resonator resonant frequencies. The power oscillator may bepowered by a power signal received from an electrical outlet. Forexample, the electrical outlet may supply the power source 104 with anAC voltage of 120 V at a frequency of 60 Hz. In other examples, thepower source may include a converter that may use a power from a powersignal, which may have a low-frequency (i.e. 60/50 Hz), to generate acarrier signal that has an oscillation frequency of one of thetransmit-resonant frequencies. The carrier signal may be modulated tocarry the power signal and may thus be the oscillating signal suppliedby the power source 104.

Furthermore, the resonant frequency ω₀ that the signal may oscillate at,also called the system resonant frequency, may be chosen by controller114 of system 100. Transmit-resonator 106 may resonate, upon receivingthe oscillating signal from source 104, and consequently, may generate afield oscillating at the system resonant frequency.

Receiver 108 may include a receive-resonator 112. The receive-resonator112 may have a high Q value and may also be configured to resonate atthe system resonant frequency. The receiver 108 may also include a load110. Thus, if receive-resonator 112 is in the range of the oscillatingfield (i.e. the field penetrates receive-resonator 112), resonator 112may wirelessly couple with the oscillating field, thereby resonantlycoupling with transmit-resonator 106. Receive-resonator 112, whileresonating, may generate a signal that may be delivered to the load 110.Note that in the implementation where the oscillating signal generatedby the power source 104 is a modulated carrier signal (generated by aconverter), the receiver 108 may include a filter network. The filternetwork may used to isolate the power signal from the modulated carriersignal. The power signal (i.e. 50/60 Hz signal) may then be delivered tothe load 110.

In example systems, there may be more than one receiver. This isdescribed below in further detail.

Wireless power delivery systems may include at least one impedancematching network configured to increase the efficiency of wireless powertransfer. FIG. 2 illustrates an impedance matching network in a system,according to an exemplary embodiment. As illustrated in FIG. 2, theimpedance matching network 202 is coupled to the transmitter 204.Further, the impedance matching network 202 may be in series, parallel,or in any other configuration with the transmit-resonator 214. In someembodiments, an impedance matching network 218 may additionally and/oralternatively be coupled to the receiver. Furthermore, the impedancematching networks 202 and 218 may each include any combination of Lmatching networks, pi networks, T networks, and/or multi-sectionmatching networks.

In some embodiments, the system may deliver a determined power to theload by configuring an impedance matching network to match a determinedimpedance. Within examples, a controller of the system may determine apower to deliver from the transmitter to the load. The controller mayuse at least the reflected impedance, from the load to the transmitter,to determine the impedance that the impedance matching network(s) may beconfigured to match. Accordingly, the system may deliver the determinedpower to the load when the impedance matching network matches thedetermined impedance.

More specifically, the controller of the system may generate a model,such as a SPICE model, of the system to determine the impedance that theimpedance matching network may match. The model may include known valuessuch as the actual impedance of the load, which the controller mayreceive from the receiver using methods described herein. However, thecontroller may need to determine the actual power supplied to the loadfrom the transmitter and the reflected impedance, from the load to thetransmitter, in order to fully characterize the model of the system(e.g. to derive the coupling factor k). The controller may use the fullycharacterized model of the system to dynamically impedance match byprecisely determining the impedance that the impedance matching circuitmay match.

Therefore, the system may include a bidirectional coupler, which may beused to determine the actual power supplied to the load from thetransmitter and the reflected impedance from the load to thetransmitter. The bidirectional coupler may be used in conjunction with acomputer and/or a controller to precisely solve for an impedance of theload connected to it. The bidirectional coupler may also be used, inconjunction with a computer and/or a controller, to precisely solve forthe amount power leaving the power source. The value of the reflectedimpedance of a load and the amount power leaving the source may be usedto adjust the impedance matching network. Accordingly, the system may beconfigured to dynamically impedance match in a single step by using thebidirectional coupler to determine the actual power supplied by thesource and the reflected impedance from the load to the transmitter.

However, the value of the reflected impedance from the load may changedue to different factors, such as a change in the coupling between atransmitter and a receiver. The coupling between a transmitter and areceiver may change due to various factors, such as a change in thedistance between the transmitter and the receiver.

For example, the receiver may move during power transfer, which maychange the coupling between the transmitter and the receiver. Suchrelative movement may change the reflected impedance of the load.Accordingly, as the reflected impedance from the load to the transmitterchanges, the controller may be configured to continuously orintermittently solve for the actual power delivered to the load and thereflected load impedance, in order to dynamically impedance match.

FIG. 3 illustrates a network representation of a system, including thebidirectional coupler 302 that is coupled in cascade between a powersource 304 and a load 306, according to an exemplary embodiment. Asillustrated in FIG. 3, the bidirectional coupler may be coupled betweenthe power source at port 2 and the rest of the system (lumped into load306) at port 8. Generally, there may be forward and reflected powerwaves at each port of the bidirectional coupler (ports 1, 3, 4, and 5).

The forward and reflected waves, and thus the power and impedance, ateach port, may be precisely determined by fully characterizing the RFproperties of the bidirectional coupler. For instance, a mathematicalrelationship between the incoming and outgoing waves on each of thebidirectional coupler 302's ports may be used to precisely calculate thepower delivered to the load 306 and the load 306's reflected impedanceback to the source 304. The mathematical relationship may use anS-parameter characterization of the bidirectional coupler 302 to relatebetween the incoming and outgoing waves on each of the bidirectionalcoupler 302's ports.

The bidirectional coupler 302 may operate by coupling forward power fromport 1 to port 3. An attenuated forward power may be coupled to port 4and sampled at measurement FWD port 6. Additionally, a small amount offorward power may also be coupled into port 5 and measured at REF port7.

Likewise, reflected power is coupled from port 3 to port 1, and anattenuated power may be coupled to port 5 and sampled at measurement REFport 7. Additionally, a small amount of reflected power may be coupledinto port 4 and measured at FWD port 6. Despite these non-idealities, ofthe forward power coupling to port 5 and the reflected power coupling toport 4, a computer and/or a controller may precisely calculate the powerdelivered to the load 306 and the load 306's reflected impedance.

The premeasured values of the mathematical relationship (A) may includea 4×4 S-parameter matrix and the input reflection coefficient, anS-parameter, of power source 302. Further, the non-idealities in theoperation of the bidirectional coupler may be accounted for bypremeasuring the 4×4 S-parameter matrix of the bidirectional coupler302. In some embodiments, the S-parameters may be premeasured using avector network analyzer (VNA). The measured S-parameters may be storedin a lookup table that a controller of system 300 may have access to.

Further, as explained above, the bidirectional coupler 302 may be usedto periodically make real-time measurements of waves that may be used tosolve for the power delivered to the load 306 and the load 306'sreflected impedance. Specifically, in order to precisely calculate thepower delivered to the load 306 and the load 306's reflected impedance,both the absolute magnitude of the power signals at ports 6 and 7 may bemeasured along with the phase of each signal with respect to the other.FWD and REF may include any measurement device or circuitry capable ofmeasuring signals, e.g., an ammeter, a voltmeter, a spectrum analyzer,etc. Furthermore, FWD and REF may send information indicative of therespective measured signals to the controller of the system.

Furthermore, certain configurations of network 300 may simplify theS-parameter characterization of the bidirectional coupler 302. Bydesign, FWD 308 and REF 310 may be impedance matched to the transmissionline that carries the signals to each port to prevent signals fromreflecting when measured at each port. For example, FWD port 308 and REFport 310 may be 50Ω terminated when a transmission line that hascharacteristic impedance (Z0) of 50Ω is used to carry the signal to eachport.

Accordingly, a controller of a wireless power delivery system may use abidirectional coupler to solve for the reflected impedance of the loadand the power delivered to the load. The system may use the solved forvalues in the model of the system to fully characterize the system. Assuch, at least the coupling factor k may be calculated. Further, thecontroller may use the model of the system to predict the amount ofpower that may be delivered to a load by adjusting the impedance thatthe impedance matching circuit may match.

Further, the controller may periodically measure the reflected impedanceof the load and the power delivered to the load, according to apredetermined time period, which may range from microseconds to tens ofseconds in length. After each measurement, the controller mayperiodically adjust at least one impedance matching network of thesystem. In an example, a controller may measure the reflected impedanceand may accordingly adjust an impedance matching network everymillisecond using the method described above. Other time intervals arepossible. Alternatively, the controller may measure the reflectedimpedance of the load and the power delivered to the load continuously.In such a scenario, the controller may continuously adjust an impedancematching network of the system to deliver a determined power to theload.

In some embodiments, the wireless power delivery system may include aplurality of receivers coupled to a single transmitter with a singlebidirectional coupler. In such a scenario, each receiver may reflect asignal to the transmitter due to a possible impedance mismatch at eachload coupled to each receiver. The controller may use the measuredvalues to fully characterize the system in order to determine animpedance that the impedance matching network may match.

In some embodiments, a plurality of receivers may be coupled to a singlebidirectional coupler. The bidirectional coupler may use time-divisionmultiplexing (TDM) to send the reflected signal of each receiver to themeasurement device during a given interval of time. The controller maythen use the method described above to solve for the reflected impedanceof each load coupled to each respective receiver.

The controller of the system may adjust at least one impedance matchingcircuit based on the measured values. In an example embodiment, a systemwith a plurality of receivers may include an impedance matching networkcoupled to the transmitter and/or to each of the receivers. However, asthe transmitter may receive different reflected impedances from eachload, it may not be possible for the controller to adjust the impedancematching network to simultaneously match the reflected impedance of eachreceiver and the impedance of the power source. Accordingly, in someembodiments, the controller may adjust at least one impedance matchingnetwork of the impedance matching networks coupled to each of thereceivers. In other embodiments, the controller may adjust the impedancematching network, coupled to the transmitter, to match the reflectedimpedance of a selected receiver from the plurality of receivers. Assuch, the selected receiver, whose reflected impedance was matched atthe impedance matching network, may proportionately receive more powerthan the other receivers in the system. In some embodiments, wirelesspower delivery to the selected receiver may be more efficient than suchpower delivery to other receivers of the plurality of receivers.

In other examples, a system with a plurality of receivers may performimpedance matching according to time-division (TDM) and/orfrequency-division (FDM) multiplexing. For instance, in a TDM scheme,each receiver may be configured to couple to the transmitter with asingle impedance matching network during a specific time interval. Thesystem may receive a reflected signal from a receiver during thespecific time interval that the receiver is coupled to the transmitter.In such a scenario, the controller may adjust the impedance matchingnetwork such that each receiver may receive maximum power during theinterval that the receiver is coupled to the transmitter. In an exampleembodiment, each receiver of the plurality of receivers may be assigneda respective time slot according to a receiver priority or a receiverorder. The time slots may be equal in duration, but need not be equal.For example, receivers with higher receiver priority may be assigned tolonger time slots than those receivers with a lower receiver priority.

In a FDM scheme, each receiver may be configured to couple to thetransmitter with on a specific respective frequency. The system mayreceive a respective reflected signal from each receiver on the specificfrequency that the receiver is coupled to the transmitter on. In such ascenario, the controller may adjust the impedance matching network(s),which may be connected to the transmitter and/or to each of thereceivers, such that each receiver may receive a determined amount ofpower.

In yet another example of a system with a plurality of receivers, acontroller may determine the power that each receiver may receivesimultaneously from the transmitter by adjusting the impedance matchingnetwork. Specifically, the impedance of the impedance matching networkmay determine, at least in part, the amount of power that each receivermay receive. For example, each receiver may receive power based on atleast a difference between the receiver's impedance and that of theimpedance matching network. Accordingly, the controller may adjust theimpedance matching network so as to increase or decrease an amount ofpower delivered to a respective receiver, based at least on thereceiver's impedance.

A controller may determine the amount of power that each receiver mayreceive from the transmitter based on various parameters. In an exampleembodiment, each receiver may be associated with a respective prioritysuch that higher priority receivers may receive more power during asingle power distribution cycle than lower priority receivers. In otherexamples, a current charging state of the receiver (if the receiver iscoupled to a load that includes a battery), may determine the amount ofpower that a receiver may receive. That is, a receiver with a lowbattery level may receive higher priority than a receiver with a fullbattery. It is understood that the controller may distribute power toeach receiver of the plurality of receivers based on a variety of otherparameters.

Within examples, a controller may receive information indicative of atleast one parameter from a receiver when authenticating the receiver. Assuch, the controller may generate a dynamic priority list based on thereceived information. In an example embodiment, the dynamic prioritylist may be updated when a receiver connects or disconnects from atransmitter. Further, a controller may store the received informationand the corresponding dynamic priority lists either locally or on aserver. In other examples, a receiver may send a controller updatedinformation if a parameter of the receiver changes after the initialsynchronization process. In other examples, a controller mayperiodically query a receiver, via a side-channel communication link,for example, to request information regarding the state of the receiver.As such, the controller may receive, via the side channel, for example,information such as the current charging state of a battery of areceiver or the current power requirements of a receiver.

In yet other examples, a system may include one or more impedancematching networks in each receiver of the plurality of receivers. Asystem may additionally or alternatively include impedance matchingnetworks in the transmitter and at least one of the receivers. In suchscenarios, a controller may be configured to adjust a plurality ofimpedance matching networks of the system such that each receiver mayreceive a determined amount of power from the transmitter.

Additionally or alternatively, the system may use the dynamic impedancematching method described above to detect a parasitic receiver.Specifically, a controller of the system may use information, such as anominal impedance, about authorized receivers to generate a circuitmodel of at least a portion of the wireless power delivery system.Additionally or alternatively, the controller may generate the circuitmodel based on an approximation, estimation, or other determination of acoupling condition between the transmitter and the receiver, which maybe based on their relative locations. Based on the circuit model, thecontroller may calculate an ideal power reception amount that it mayreceive from each receiver. Accordingly, the controller may compare thecalculated ideal power received and the actual power received. If theideal and actual power received are not equal within a specified marginof error, the controller may determine that a parasitic device may bepresent in the system. For example, the controller may determine that aparasitic device may be present in the system if the value of thecalculated power received varies by more than 10% of the value of theactual power received. Additionally or alternatively, the controller mayuse other methods disclosed herein to identify parasitic receivers.

A. Coupling Modes

A transmitter and a receiver of a wireless power delivery system mayestablish a wireless coupling resonant link, and thus become resonantlycoupled, via various coupling modes. Each coupling mode is associatedwith a type of resonator that may be included in a transmitter and/or areceiver. Accordingly, a system may excite a type of resonator so as toprovide a wireless resonant link via the associated coupling mode.Furthermore, the system may maintain multiple wireless resonant links ofdifferent coupling mode types at any given time. Within examples, atransmitter and a receiver of a system may include at least one of threeresonator types. As such, the operational state of a system may utilizeat least one of three resonant coupling modes.

FIG. 4A and FIG. 4B illustrate an inductive resonant coupling mode, thefirst coupling mode, according to an exemplary embodiment. Each oftransmit-resonator 402 and receive-resonator 404 may include at least aninductor. Further, each resonator may be configured to resonate at leastat the system resonant frequency of system 400. Transmit-resonator 402may resonate upon receiving a signal, from power source 406, that isoscillating at the system resonant frequency. Thus, transmit inductor408 of transmit-resonator 402 may generate a magnetic field oscillatingat the system resonant frequency. Receive-resonator 404 may couple withthe oscillating magnetic field if it is within proximity to thetransmit-resonator 402. As a result, a wireless coupling resonant linkmay be established. Coupled receive-resonator 404 may then resonate, andmay therefore generate a signal that may be delivered to load 412.

Additionally or alternatively, the system may include a transmitterand/or a receiver that include a capacitive resonator, which may beoperable to couple the transmitter and the receiver. In an exampleembodiment, each of the transmitter capacitive resonator and thereceiver capacitive resonator may include at least a capacitor. Thetransmit-resonator may resonate upon receiving, from the power source, asignal oscillating at the system resonant frequency. As thetransmit-resonator resonates, the capacitor of the transmit-resonatormay generate an electric field oscillating at the system resonantfrequency. The receive-resonator, if in proximity to thetransmit-resonator, may couple with the oscillating electric field;thereby establishing a wireless coupling link between the transmitterand the receiver. As such, the receive-resonator may resonate, and maytherefore generate a signal that may be delivered to a load coupled tothe receiver.

In an example embodiment, a system may include at least one of two typesof capacitive resonators, each of which may be associated with arespective coupling mode. The two capacitive resonators differ in theconfiguration of their respective capacitors. The first capacitiveresonator may include a common mode capacitor, which may support acapacitance between a single conductor and ground. A common modecapacitive resonator may be operable to provide a wireless coupling linkvia a coupling mode termed common mode. The second capacitive resonatortype may include a differential mode capacitor, which may support acapacitance between two conductors. A differential mode capacitiveresonator may be operable to provide a wireless coupling link via acoupling mode termed differential mode.

FIG. 5A, FIG. 5B, and FIG. 5C illustrate a system, in threerepresentations, that includes a common mode capacitive resonator,according to an exemplary embodiment. Each of transmit-resonator 502 andreceive-resonator 504 includes a common mode capacitive resonator. Assuch, each resonator includes a common mode capacitor that includes aconductor and ground reference 506. Ground reference 506 may conductcurrent to complete the circuit of transmitter 508 and receiver 510.Further, transmitter 508 may be coupled with power source 512 that maybe connected on one end to ground reference 506 and on the other end toat least transmitter conductor 514. Optionally power source 512 need notbe connected to the ground reference 506. Transmit-resonator 502 mayresonate upon receiving, from power source 512, a signal that isoscillating at the system resonant frequency. As the transmit-resonator502 resonates, common mode capacitor 516 of the transmit-resonator 502may generate an electric field oscillating at the system resonantfrequency. Receiver 510 may include load 518 that may be connected onone end to ground reference 506 and on the other end to receiverconductor 520. If within the near field of transmit-resonator 502, thereceive-resonator 504 (which includes common mode capacitor 522) maycouple with the oscillating electric field, thereby establishing awireless resonant coupling link. As such, receive-resonator 504 mayresonate, and may generate a signal that may be delivered to the load.

In some embodiments, the ground reference of the common mode capacitorsmay be connected to earth ground via a direct or an indirect connection.For example, the ground reference may include the infrastructure of abuilding housing the wireless power system, which may include anindirect connection to earth ground. In other examples, the groundreference may include a conductive object connected to common modecapacitors. As such, the conductive object may provide a conductivereturn path in a circuit including a transmitter and/or a receiver. FIG.5B illustrates the circuit diagram of a system using common mode wherethere is a conductive path through ground, as explained above. FIG. 5Cillustrates the circuit diagram of a system using common mode wherethere is a capacitive connection to ground, as explained above.

FIGS. 6A and 6B illustrates a system 600, in two representations, thatincludes a differential mode capacitor, according to an exemplaryembodiment. Each of transmit-resonator 602 and receive-resonator 604 mayinclude at least one capacitor. Power source 606 may supply a signaloscillating at a system resonance frequency to transmit-resonator 602.Transmit-resonator 602 may resonate upon receiving the signal fromsource 606. As transmit-resonator 602 resonates, transmitterdifferential mode capacitor 608 may generate an electric fieldoscillating at the system resonant frequency. Receive-resonator 604, ifin proximity to the transmit-resonator 602, may couple with theoscillating electric field. As such, a wireless resonant coupling linkmay be established between the transmitter and the receiver.Furthermore, receiver differential mode capacitor 610 may resonate, andmay therefore generate a signal that may be delivered to load 612coupled to receiver 614.

In example embodiments, a system may establish a wireless resonantcoupling link between a transmitter and a receiver according to one ormore coupling modes that include a capacitive resonant coupling mode andan inductive resonant coupling mode. A transmitter and a receiver mayeach include the resonators necessary to establish a wireless link ineach of the coupling modes. Furthermore, a wireless coupling link may bemaintained between the transmitter and the receiver that utilizesdifferent coupling modes simultaneously or individually. In someexamples, the resonators may include a single circuit element that maybe configured to operate either as an inductor, a capacitor, or both. Inan example, an element may include coils shaped like a pair of conductorplates, such that the element may operate as an inductor and/or acapacitor. In other examples, a transmitter or receiver may includemultiple resonators arranged in a resonator bank. The resonator bank mayinclude at least one resonator that may include an inductor, and atleast one resonator that may include a capacitor. Accordingly, theresonator bank may be configured to establish wireless resonant couplinglinks in capacitive and inductive resonant coupling modes.

FIG. 7 illustrates a flowchart showing a method 700 that may establish awireless resonant coupling link between a transmitter and a receiver ofa system, according to an exemplary embodiment. In some embodiments,method 700 may be carried out by a controller of a system.

Furthermore, as noted above, the functionality described in connectionwith the flowcharts described herein can be implemented asspecial-function and/or configured general-function hardware modules,portions of program code executed by one or more processors forachieving specific logical functions, determinations, and/or stepsdescribed in connection with the flowchart shown in FIG. 7. For examplethe one or more processors may be part of controller 114. Where used,program code can be stored on any type of non-transitorycomputer-readable medium, for example, such as a storage deviceincluding a disk or hard drive.

In addition, each block of the flowchart shown in FIG. 7 may representcircuitry that is wired to perform the specific logical functions in theprocess. Unless specifically indicated, functions in the flowchart shownin FIG. 7 may be executed out of order from that shown or discussed,including substantially concurrent execution of separately describedfunctions, or even in reverse order in some examples, depending on thefunctionality involved, so long as the overall functionality of thedescribed method is maintained.

As shown by block 702, of FIG. 7, method 700 may involve determining anoperational state of a system. The determined operational state mayinclude at least one coupling mode. For example, the determinedoperational state may include any of the wireless coupling modesdescribed herein. Within examples, the determined operational state maybe determined by a controller of the system. As shown by block 704,method 700 further includes causing a power source that is coupled to atransmitter of a system to provide a signal at an oscillation frequency.For example, the oscillation frequency may be one of the one or moreresonant frequencies of the transmitter. In some embodiments, theoscillation frequency may be a frequency within a range of resonantfrequencies of the transmit-resonator.

Accordingly, as shown by block 706, a transmit-resonator may resonate atthe oscillation frequency upon receiving the signal from the powersource of the system. The oscillating transmit-resonator may generate afield oscillating at the oscillation frequency. In some embodiments, thetransmit-resonator may generate a field that may be oscillating at afrequency within a range of resonant frequencies of thereceive-resonator. As shown by block 708, if a receive-resonator islocated within the range of the oscillating field generated by thetransmit-resonator, the receive-resonator may also resonate at theoscillation frequency. As a result, as shown by block 710, a wirelessresonant coupling link may be established according to the determinedoperational state. Finally, method 700 may cause the transmitter todeliver electrical power to each of the one or more loads via theestablished wireless resonant coupling link, as shown by block 712.

FIG. 8 illustrates different combinations of coupling modes that mayform wireless resonant coupling link, according to an exemplaryembodiment. In an example embodiment, a system may include a transmitterand a receiver both having three different types of resonator elements(e.g. an inductor, a common-mode capacitor, and a differential-modecapacitor). Accordingly, a wireless resonant coupling link between thetransmitter and the receiver may include various combinations of thethree different coupling modes. Accordingly, combinations 1-7 eachinclude supporting a wireless resonant coupling link via at least onecoupling mode. Operational state 8 represents when the system is notoperating or when the transmitter and receiver are not coupled via awireless resonant coupling link. Within examples, the variouscombinations of coupling modes forming the wireless coupling linkbetween the transmitter and the receiver may be determined andcontrolled by a controller. In other examples, a user may provide aninput to the controller that may direct the system to form a wirelessresonant coupling link with a given combination of coupling modes.

In an example embodiment, a system may establish wireless resonantcoupling links between a transmitter and a plurality of receivers. Insuch a scenario, the plurality of receivers may all operate in a singleoperational state to establish simultaneous links to the transmitter. Inother scenarios, each of the receivers may establish a wireless resonantcoupling link with the transmitter using a different coupling mode.Transmitters of such systems may include a resonator bank configured toenable simultaneous links with a plurality of receivers via one or morecoupling modes.

As explained elsewhere herein, a system may employ time divisionmultiple access (TDMA) to establish a wireless resonant coupling linkthat may be shared by a plurality of receivers. Specifically, thewireless resonant coupling link may be divided into different time slotswithin a given time frame. As such, each receiver of the plurality ofreceivers may receive electrical power from the transmitter during anassigned time slot within the given time frame. In other words, withinthe given time frame, the transmitter may distribute power to a givenreceiver during a given time slot. Each receiver may be assigned toreceive power during one or more time slots within the time frame.

FIG. 9A illustrates a TDMA wireless resonant coupling link, according toan exemplary embodiment. Specifically, the ten time slots (T1-T10) mayrepresent a single time frame of power distribution. The samedistribution may be repeated in subsequent time slots T11-T20 and/ortime frames (not shown). Furthermore, a controller of the system mayassign each receiver of the system one or more time slots during whichthe receiver may receive power from the transmitter. In this example,receivers 1-4 are configured to receive power from the transmitterduring various time slots of this time frame, whereas receiver 5 is notconfigured to receive power. In such a scenario, a controller may assignreceivers 1-4 specific time slots during which they may receive powerfrom the transmitter. The power may be transferred to a receiver duringa given time slot according to any of the modes of operation of asystem. Within examples, the controller may determine the operationalstate (e.g., the coupling mode type(s)) of each receiver during eachinterval of time. In other examples, the operational state may be inputby a user of the respective receiver.

FIG. 9B illustrates a TDMA wireless resonant coupling link, according toan exemplary embodiment. Similar to the system illustrated in FIG. 9A,the ten time slots (T1-T10) may represent a single frame of powerdistribution. However, as illustrated in FIG. 9B, more than one receivermay receive power simultaneously from the transmitter. Furthermore, eachreceiver may receive power according to an of the modes of operation ofthe system. In some examples, the receivers receiving powersimultaneously may receive power according to the same mode ofoperation. In other examples, the receivers receiving powersimultaneously may receive power according to different modes ofoperation.

In accordance with some embodiments, the components (e.g., transmitterand receiver) of a system may include circuit elements (shown as element212 in FIG. 2, element 414 in FIG. 4, element 524 in FIG. 5, and element616 in FIG. 6), such as inductors, capacitors, transistors, inverters,amplifiers, rectifiers, varactors, relays, diodes, transmission lines,resonant cavities and switches, which may be arranged to facilitateswitching between the different coupling modes of a system. For example,a system may switch between the different modes by having both a coiland one or two (or more) conductors in a combination of series-parallelconnections. In other examples, a system may dynamically suppress orenhance a coupling mode by dynamically adding lumped element reactivecomponents in series or parallel between the elements of the resonatorof each mode.

In some examples, the operational state of a system may be determined bya controller of the system. For example, a controller may determine themode of the operation of the system based on data that it may receivefrom a receiver, such as the receiver's power demands, preferredoperational state, and location. Alternatively or additionally, thecontroller may determine the operational state based on data that may beinput by a user of the system. Furthermore, the operational state may bedetermined based on the status of the system and/or environmentalconditions.

In some embodiments, a controller may switch the operational state inresponse to detecting a parasitic device (using methods describedherein) that may be diverting power from a legitimate receiver. In anexample, a system may be operating in a state that utilizes common moderesonant coupling. However, a controller may detect a parasitic devicethat may also be coupled to the transmitter using common mode. Inresponse, the controller may stop wireless power delivery via the commonmode, and may enable wireless power delivery via a differentialcapacitive coupling mode, an inductive resonant coupling mode, or both.In other embodiments, a controller may use environmental conditions todetermine the system's operational state. For example, a controller mayreceive information indicative of a presence of high ferrite contentobjects in the system's environment. Accordingly, the controller maydetermine to operate in a mode that does not utilize inductive resonantcoupling mode.

A controller may also determine an amount of electrical power that asystem may deliver to each load in the system. The controller may alsomake a determination of how much electrical power to deliver to eachload via each available coupling mode in the system. Accordingly, in anexample, the controller may cause the power source to direct thedetermined amount of power to a resonator bank and further control thedelivery of power to the respective receivers via the respectivedetermined coupling modes.

Furthermore, external elements may be installed in a system'senvironment, which may be configured to improve or otherwise modify theperformance of the system. In some embodiments, field concentrators maybe configured to shape an oscillating magnetic field (of an inductiveresonator), an oscillating electric field (of a capacitive resonator),or both. For example, high permeability materials, such as ferrites, maybe installed in a system's environment. In an example embodiment, whilethe system is operating in inductive resonant coupling mode, the highpermeability material may be arranged so as to shape the oscillatingmagnetic field and extend its range. Similarly, high permittivitydielectric materials may be arranged in a system's environment. Acapacitor of the system may utilize the high permittivity dielectricmaterials to increase or otherwise modify its capacitance, and henceadjust the properties of the electric field produced by a resonantcapacitor. Furthermore, conductors may also be arranged in a system'senvironment so as to affect the magnetic and/or the electric fieldproduced by the system's resonators.

Within examples, a system may include circuit elements that may be usedas necessary in the system to implement the system's functionality. Forexample, a system may include circuit elements such as inverters,varactors, amplifiers, transmission lines, resonant cavities rectifiers,transistors, switches, relays, capacitors, inductors, diodes, andconductors. A relay may be used for switching between circuit elementsconfigured to operate each coupling mode. As explained herein, a switchmay connect a load to a receiver, such that the load is switchablycoupled to the receive-resonator. Other examples of possible uses forvarious circuit elements are possible.

B. Power Transfer to Legitimate Receiver(s)

FIG. 10 illustrates a resonant wireless power delivery system 1000according to an example embodiment. The system 1000 includes a powersource 1010, a transmitter 1020, and a receiver 1040. The transmitter1020 receives power from the power source 1010 and wirelessly transfersthis power to the receiver 1040. The transmitter 1020 may be one of aplurality of transmitters. The receiver 1040 is one of a plurality ofreceivers that may receive power from the transmitter 1020.

The transmitter 1020 includes a transmit-resonator 1022, and thereceiver 1040 includes a receive-resonator 1042. The transmit-resonator1022 is supplied with a power signal from the power source 1010oscillating at a resonant frequency ω₀. As described above, thetransmit-resonator 1022 resonates at the resonant frequency ω₀ andgenerates a field that oscillates at the resonant frequency ω₀. Thereceiver-resonator 1042 is correspondingly configured to resonate at theresonant frequency ω₀. The receiver 1040 is placed in sufficientproximity to the transmitter 1020 to couple the receive-resonator 1042with the field generated by the transmit-resonator 1022, e.g., thereceiver-resonator 1042 is within the field of the transmit-resonator1022 depending for instance on the quality factor Q as described above.This coupling establishes a resonant power transfer link 1002 thatprovides a wireless conduit for power transfer between thetransmit-resonator 1022 and the receive-resonator 1042. As alsodescribed above, the transmit-resonator 1022 and the receive-resonator1042 may be coupled via an oscillating magnetic field and/or anoscillating electric field. In particular, the coupling may include anyone or more of the following three modes: (i) inductive mode, (ii)differential capacitive mode, and (iii) common capacitive mode.

While the receive-resonator 1042 resonates in response to theoscillating field, a rectifier 1048 or other power conversion circuitmay convert power from the receive-resonator 1042 and subsequentlydeliver the power to a load 1060. While the load 1060 is incorporatedinto the receiver 1040 as illustrated in FIG. 10, some embodiments mayinclude loads that are physically separate or otherwise apart from thereceiver 1040.

As shown in FIG. 10, the transmitter 1020 includes a controller 1024. Inan example embodiment, the controller 1024 may determine what couplingmode(s) to employ and may control various elements of the transmitter1020 so as to establish and/or maintain wireless resonant coupling linksaccording to the determined coupling mode(s). The controller 1024 mayalso determine the amount of power that is transferred via therespective coupling mode(s).

As also described above, higher efficiencies can be achieved byadjusting impedances (resistance and/or reactance) on the transmittingside and/or the receiving side, e.g., impedance matching. Accordingly,the transmitter 1020 may include an impedance matching network 1026coupled to the transmit-resonator 1022. Similarly, the receiver 1040 mayinclude an impedance matching network 1046 coupled to thereceive-resonator 1042.

In an example embodiment, a plurality of devices and objects may bepresent within a local environment of the transmitter 1020. In such ascenario, the example system 1000 may be configured to distinguishlegitimate receivers from illegitimate devices that are not intendedrecipients of power transfer. Without an ability to discriminate betweenpossible recipients of power transfer, illegitimate devices may act asparasitic loads that may receive power from the transmitter withoutpermission. Thus, prior to transferring power to the receiver 1040, thetransmitter 1020 may carry out an authentication process to authenticatethe receiver 1040. In an example embodiment, the authentication processmay be facilitated via a wireless side-channel communication link 1004.

The transmitter 1020 may include a wireless communication interface 1028and the receiver 1040 may include a corresponding wireless communicationinterface 1048. In such a scenario, the transmitter 1020 and thereceiver 1040 may establish a side-channel communication link 1004 via awireless communication technology. For instance, classic BLUETOOTH® orBLUETOOTH® LOW ENERGY (BLE) (2.4 to 2.485 GHz UHF) or WIFI™ (2.4 GHzUHF/5 GHz SHF) may be employed to provide secure communications betweenthe transmitter 1020 and the receiver 1040. Other wireless communicationprotocols are possible and contemplated. As shown in FIG. 10, theside-channel link 1004 communicatively couples the transmitter 1020 andthe receiver 1040 over a secondary channel that is separate from theresonant power transfer link 1002. In alternative embodiments, however,the transmitter 1020 and the receiver 1040 may employ the same channelto transfer power and communicate information as described herein, e.g.,by modulating aspects of the power transfer to communicate theinformation.

In an example embodiment the transmitter 1020 can communicate with thereceiver 1030 over the side-channel communication link 1004 to determinethat the receiver 1040 is authorized or otherwise permitted to receivepower. The receiver 1040 may be configured to provide any type ofinformation and/or acknowledgement required by the transmitter 1020 toauthenticate the receiver 1040. For instance, the receiver 1040 maytransmit an authentication code, a message, or a key to the transmitter1020. In such scenarios, a device without the ability to establishside-channel communications with the transmitter 1020 may not beidentified as a legitimate device.

The receiver 1040 may also include a controller 1044. As such, thecontrollers 1024, 1044 can conduct communications via the side-channellink 1004 and process the information exchanged between the transmitter1020 and the receiver 1040.

As described above, when power is transferred from the transmitter 1020to the receiver 1040, power may be reflected back to the transmitter1020 As FIG. 10 illustrates, the transmitter 1020 may include abi-directional RF coupler 1030 to measure the reflected power as alsodescribed above. Using measurements from the bi-directional RF coupler1030, an optimal efficiency for the power transfer link 1002 may beascertained, and the impedance(s) on the transmitting and/or receivingsides can be adjusted via the impedance matching networks 1026, 1046 soas to optimize or otherwise modify power delivery efficiency.

The impedance associated with the receiver 1040 may be determined basedon the reflected power detected by measurement devices in conjunctionwith the bi-directional RF coupler 1030. If a nominal impedance (e.g., adesigned impedance) of the receiver 1040 is known, a difference betweenthe nominal impedance and the calculated impedance based on themeasurement of reflected power may indicate a presence of one or moreparasitic loads. Such parasitic loads may include illegitimatereceivers. Using the side-channel communication link 1004 establishedbetween the transmitter 1020 and the receiver 1040, the receiver 1040may be operable to communicate its nominal impedance to the transmitter1020. Thus, the calculation of impedance using the bi-directional RFcoupler 1030 may enable the identification of parasitic loads as well asenable dynamic impedance matching as disclosed elsewhere herein. Theimpedance(s) of the transmitter 1020 and/or the receiver 1040 can beadjusted via the impedance matching networks 1026, 1046 to account forthe parasitic loads.

As described herein, the transmitter 1020 may be operable to identifythe existence of the legitimate receiver 1040 through authenticationcommunications via the side-channel communication link 1004.Additionally or alternatively, the transmitter 1020 may be operable todistinguish the legitimate receiver 1040 from other legitimate orillegitimate devices by other methods. In particular, the transmitter1020 may be operable to control the power transfer link 1002 and thecommunication over the side-channel communication link 1004 with thesame receiver 1040.

FIG. 11 illustrates an example method 1100 for confirming that the powertransfer link 1002 and the side-channel communication link 1004 areestablished with the same receiver 1040. In step 1102, the transmitter1020 and the receiver 1040 may establish wireless communications via theside-channel communication link 1004. In step 1104, the receiver 1040sends authentication information to the transmitter 1020 viaside-channel communication link 1004, and in step 1106, the transmitter1020 evaluates the authentication information to determine that thereceiver 1040 is permitted to receive power.

Having identified the existence of the legitimate receiver 1040 via theside-channel communication link 1004, the transmitter 1020 may attemptto determine that the corresponding power transfer link 1002 isoccurring with the same receiver 1040. Accordingly, in step 1108, thetransmitter 1020 attempts to send a predetermined amount of power to thereceiver 1040 via the power transfer link 1002. In step 1110, thetransmitter 1020 communicates with the receiver 1040 via theside-channel communication link 1004 to confirm that the receiver 1040received the power transmission from step 1108. For instance, thereceiver 1040 can detect and report the power received. If the receiver1040 fails to provide information confirming the power transmission fromthe transmitter 1020, the transmitter 1020 in step 1112 can re-attemptto establish the power transfer link 1002 with the receiver 1040. Witheach re-attempt, the transmitter 1020 can change the amount of powerand/or modulate an impedance in an attempt to account for any parasiticloads that may be interfering with the power transfer to the correctreceiver 1040. Additionally or alternatively, the transmitter 1020 canchange the coupling mode(s) for the power transfer link. Once the powertransfer link 1002 to the correct receiver 1040 is established, thetransmitter 1020 can further modulate impedance, if necessary, andcontinue to transfer power to the receiver 1040.

In view of the foregoing, the side-channel communication link 1004 maybe employed to identify and authenticate the receiver 1040 and toestablish and adjust aspects of the power transfer link 1002,particularly to account for parasitic loads. Specifically, theside-channel communication link 1004 and the power transfer link 1002may enable a variety of authentication protocols so as to provide securecommunications and power delivery. For example, the transmitter 1020 andreceiver 1040 may be operable to conduct a password authenticationprotocol (PAP), a challenge-handshake authentication protocol (CHAP),multi-factor authentication, or another type of cryptographic protocol.In general, however, the transmitter 1020 and the receiver 1040 mayemploy the side-channel communication link 1004 to exchange any type ofinformation to manage any aspect of the power transfer link 1002.

In an example embodiment, the system 1000 may help ensure theavailability of the side-channel communication link 1004 byintermittently or continuously transmitting a certain amount of powervia a predetermined wireless resonant coupling link configuration. Thistransmission 1006 can power the wireless communication interface 1048and allow it to remain active even if other aspects of the receiver 1040do not receive power. As such, the receiver 1040 may receive sufficientpower to establish initial communications with the transmitter 1020.Thereafter, the receiver 1040 may establish the power transfer link1002. For instance, the transmission 1006 may provide a low power, e.g.,approximately 1 W. In such a scenario, the power distribution efficiencyof the transmission 1006 is less of a concern at relatively low powers.

As described above, the controller 1024 may determine what coupling modeto employ in the example system 1000. The controller 1024 may selectcoupling mode(s) based on the identification of parasitic loads. Forinstance, the transmitter 1020 may deliver power to the receiver 1040via a common capacitive mode during a first time period. However,subsequent to the first time period, the controller 1024 may detect aparasitic device that may also be coupled to the transmitter 1020 viacommon capacitive mode. Consequently, the controller 1024 may cause thetransmitter 1020 and/or the receiver 1040 to a switch to differentialcapacitive mode and/or inductive mode.

As shown in FIG. 12, the transmitter 1020 may also employ time-divisionand/or frequency-division multiplexing for the power transfer links 1002a-d to a plurality of legitimate receivers 1040 a-d, respectively.Although FIG. 12 may illustrate four receivers, it is understood thatany number of receivers may receive power from a transmitter accordingto the present disclosure.

Multiplexing may allow the transmitter 1020 to control how power isdistributed to the receivers 1040 a-d. For example, with time-divisionmultiplexing, power transfer during a given time period may be assignedto one or more specified receivers. With frequency-divisionmultiplexing, power may be transferred to specified receivers viarespective frequencies. In such a scenario, the transmitter may beconfigured to transmit a plurality of the respective frequenciessimultaneously. Thus, as illustrated in FIG. 12, the power transferlinks 1002 a-d may occur at various designated time and/or frequencycombinations (t, f)₁, (t, f)₂, (t, f)₃, (t, f)₄, respectively.Accordingly, the use of multiplexing may promote coordinated deliveryand availability of power to the receivers 1040 a-d.

Although the transmitter 1020 may transfer power to one receiver via asingle power transfer link having a particular time and/or frequencycombination as shown in FIG. 12, the transmitter 1020 in alternativeembodiments may transfer power to one receiver via multiple powertransfer links having different time and/or frequency combinations. Suchan approach provides some redundancy in case the transmitter 1020 isunable to transfer power with one or more of the power transfer links,e.g., due to interference from illegitimate receiver(s). The transmitter1020 can fall back on the remaining power transfer links to transferpower to the receiver without interruption. In general, the transmitter1020 can establish and selectively use any number of power transferlinks with a single receiver, where the power transfer links usedifferent respective time and/or frequency combinations.

The transmitter 1020 and the receivers 1040 a-d may employ side-channelcommunication links 1004 a-d as described above to coordinate themultiplexed transfer of power. For instance, the transmitter 1020 cancommunicate what time slots and/or which frequencies will be employed totransfer power to the receivers 1040 a-d. In an example embodiment,wireless power delivery utilizing time and frequency multiplexing may bemore secure than other wireless power delivery methods at least becausethe multiplexing scheme employed by the transmitter 1020 is likely to beunknown to illegitimate devices.

Without multiplexing, illegitimate devices with impedances or loadprofiles similar to legitimate devices might receive power withoutpermission. In cases where power resources may be limited, unpermitteduse of such power resources might result in denial of power tolegitimate receivers. Thus, multiplexing may allow more efficient androbust power transfer from the transmitter to any number of legitimatereceivers even in the presence of illegitimate or parasitic receivers.

It is understood that the use of a side-channel link is not limited tothe examples above. In an alternative implementation, for instance, atransmitter and a plurality of receivers may be pre-programmed withinformation regarding the multiplexing scheme for power delivery to theplurality of receivers. Additionally or alternatively, the transmittermay be pre-programmed with information regarding the nominal impedancesfor the receivers. In some cases, the receivers may have the sameimpedance. A side-channel communication link can then be used tocommunicate information that is not pre-programmed into the transmitterand/or the receivers. For instance, if a wireless power delivery systemis pre-programmed with the multiplexing scheme as well as informationrelating to the nominal impedances for the receivers, a side-channelcommunication link can be used by a receiver to report the powerreceived it has received so that the existence of any parasitic loadscan be determined as described above.

C. Repeaters

In accordance with example embodiments, the system may include one ormore resonant repeaters (or simply repeaters) configured to spatiallyextend the near field region of the oscillating field. Doing so mayenlarge the region around the transmitter within which receivers may beplaced in order to resonantly couple to, and receive power from, theoscillating field, as described above. In one example, a resonantrepeater may include a repeat resonator configured to resonate at theresonant frequency ω₀ of the system (the system resonant frequency) whenpositioned in the transmitter near field. Driven by the resonatingrepeat resonator, the repeater may then repeat the transmitter nearfield, thereby extending the range of the near field. Such repeater maybe passive, in the sense that they may be powered only by the near fieldin which they are positioned.

In an embodiment, a resonant repeater may receive a power signal via awireless resonant coupling link that may have been established with thetransmitter or with another repeater. As explained above, the wirelessresonant coupling link may be established when the repeater couples witha first near field of the transmitter or of another repeater. Therepeater may then emit the signal via a second wireless coupling linkestablished with another repeater and/or a receiver. Further, the signalthat is emitted by the repeater has an associated near field, with whichanother repeater and/or a receiver may couple. In some embodiments, therepeater may emit a signal such that the near field associated with theemitted signal is farther away from the transmitter than the extent ofthe first near field.

In further accordance with example embodiments, a plurality of repeatersmay be configured in a chain-like configuration, such that eachsubsequent repeater in the chain resonantly repeats the near field of anearlier link in the resonant repeater chain. The plurality of repeatersmay also be configured in array-like configuration. In such scenarios,the transmitter near field may be continually extended beyond itsoriginal range. Within examples, a repeater may establish severalwireless coupling links with one or more receivers and/or with one ormore repeaters. In some embodiments, a repeater may transmit power toone or more repeaters and/or to one or more receivers via a singlewireless resonant coupling link.

Furthermore, each repeater may be configured to couple with a magneticnear field and/or an electric near field. Each repeater may also beconfigured to repeat a magnetic near field and/or an electric nearfield. A repeater may couple with, and may repeat, various field typesdepending at least on the operational state of the system. For example,each repeater may couple with a transmitter or another repeater using atleast one coupling mode, according to the operational state of thesystem. Accordingly, each repeater may include at least one of a commonmode resonator, a differential mode resonator, and an inductiveresonator. The one or more resonator types that may be included in arepeater may be collectively referred to as a repeat resonator.

While the transmitter near field can be extended using one or morerepeaters, there may, however, be physical limitations to how far thenear field may be extended by chaining repeaters. Specifically, the nearfield will decay to some degree from one repeater to the next, so thateach repeated field produced by a passive repeater may have slightlylower, or substantially lower, average energy density than that producedby an earlier passive link. Thus, an accumulated decay may eventuallyyield little or no power transfer.

In accordance with example embodiments, the physical limitation due todecay of the near field may be overcome by including additionalcapabilities in the repeaters. For example, each repeater may include animpedance matching circuit that may improve the power transferefficiency from one repeater to another. In other examples, a system maymitigate decay of the near field by using active repeaters, each ofwhich includes an independent (secondary) power source. As such, theactive repeaters can “inject” additional power into the repeated fields.In one example embodiment, all of the repeaters of the system are activerepeaters. In another example embodiment, only some of the repeaters areactive repeaters, while others may be passive repeaters.

Within examples, an active repeater may “inject” additional power intothe repeated fields by applying a signal gain to the power signal thatthe active repeater receives from the transmitter or another repeater.The repeater may then emit the signal to another repeater or a receiver.In some embodiments, a repeater may be configured to apply a predefinedgain to the received signal. In other examples, a controller of thesystem may determine the gain that each active repeater applies to thereceived signal. For example, a controller may direct the activerepeater to apply a gain that is equivalent to the propagation losses ofthe signal. Thus, a load may receive the signal that has the samemagnitude as the original signal provided by the primary power source.Furthermore, in such a scenario, the extent of each repeater near fieldmay be similar to the extent of the transmitter near field. In otherexamples, an active repeater may be configured to emit a signal that maybe larger in magnitude than the signal that was emitted by thetransmitter.

Another physical limitation, discussed below, may arise due toaccumulated phase delay across chained repeaters. Also as discussedbelow, compensation for the effects of phase accumulation may beachieved by introducing adjustable phase shifts in repeaters, inaccordance with example embodiments.

D. Metamaterials and Phase Shift Adjustment

Generally, a phase shift may occur between the near field that arepeater couples with and the near field that is repeated by therepeater. Specifically, the phase shift may occur due to a propagationdelay of the power signal as the signal is received and subsequentlyemitted by a repeater. Alternatively or additionally, the phase shiftmay occur, at least in part, due to propagation of the electromagneticwave in a medium (e.g., air) between the transmitter and the repeater.Accordingly, each repeated near field produced by a given repeater willbe shifted in oscillatory phase with respect to that produced by anearlier repeater. However, if the accumulated phase shift acrossrepeaters in a chain approaches one-quarter of the resonant wavelength,the transmitter and the chain of repeaters will appear to behave like aradiating antenna array, and thus radiate power as an electromagneticwave in a far-field region of the antenna array. Such radiative behaviormay result in overall power loss and inefficient power delivery.

Radiation loss due to cumulative phase delay across a chain or an arrayof repeaters may be suppressed or eliminated by including one or morephase adjustment elements in some or all of the repeaters. Specifically,a repeater having a phase adjustment element may adjust the phase of itsrepeated near field. By appropriate phase adjustment, the near field ofthe system may be extended without becoming a radiating antenna array.Phase adjustment may be provided in a repeater by lumped elements, suchas inductors and capacitors, or by use of metamaterials, or both.Additionally and/or alternatively, the phase may be adjusted bydistributed elements that may have capacitive and/or magneticproperties.

A repeater may include phase adjustment elements that may be configuredto adjust the phase of a magnetic and/or electric field. As explainedabove, a near field type may depend on the operational state of thesystem. For example, a system may operate using inductive resonantcoupling and/or capacitive resonant coupling. As such, the near fieldthat is produced by a transmitter, and which is then repeated by eachrepeater, may be a magnetic field (associated with inductive resonantcoupling) and/or an electric field (associated with capacitive resonantcoupling). Within examples, the phase adjustment elements included ineach repeater may include any circuit element operable to adjust theinduced magnetic near field and/or the induced electric near field thatis associated with each signal emitted by each repeater. For example,each repeater may include lumped or distributed reactive components(i.e. capacitors and inductors) arranged to adjust a phase of a receivedsignal before and/or while repeating the signal.

In some embodiments, the phase adjustment elements of a repeater may beoperable to shift the phase of a near field that the repeater may couplewith. The repeater may subsequently regenerate the phase shifted nearfield such that another repeater and/or a receiver may couple with thephase shifted near field. More specifically, the repeater may shift thephase of the near field with respect to a phase of the near field at therespective location of the repeater. Alternatively, the repeater mayshift the phase, of the near field that it couples with, with respect toa reference phase of the oscillating field generated by thetransmit-resonator of the transmitter.

In accordance with some embodiments, a repeater may include ametamaterial configured to couple with a near field, and to repeat thenear field with a finite phase shift. Generally, a metamaterial is amaterial that may have properties not found in nature, due to the factthat its properties depend on its structure rather than on thecomposition of its elements. As a non-limiting example, the metamaterialmay include a split-ring resonator. In some embodiments, a metamaterialmay be configured to have a negative permeability, μ, and a negativepermittivity, ϵ. Such metamaterials may have a negative index ofrefraction, and thus may be referred to as negative index metamaterials(NIM). The index of refraction of a material may be defined as the ratioof the speed of light to the phase velocity in a material.

Therefore, a field that is incident on or that couples with an MM may berefracted with a negative phase velocity. Accordingly, a NIM may beconfigured to adjust the phase of a field oscillating at a resonantfrequency to which it may couple. In some embodiments, all of therepeaters of a system may include a NIM with negative permeability andpermittivity at the resonant frequency. In other embodiments, some ofthe repeaters of a system may be NIM, while other repeaters may berepeaters that include lumped/distributed reactive components.

Within examples, NIM may be configured such that the material may beadjustable so as to controllably shift the phase of a field (magneticand/or electric) at least based on a given resonant frequency. Asexplained herein, a repeater may couple with fields oscillating within arange of different frequencies, as the resonant frequency of the systemmay be adjusted dynamically. Accordingly, the metamaterial (NIM)repeater may be tunable so as to couple with, and shift the phase of,fields oscillating at different frequencies. In some embodiments, a metamaterial (NIM) repeater may be an active repeater, which may “inject”power into the repeated field with the shifted phase.

Within examples, each repeater may be configured to adjust the phasesuch that the near field of the emitted signal (i.e. repeated field) isin phase (or nearly so) with the near field produced by the earlier linkin the array of repeaters. Accordingly, the phase of each repeated fieldmay be “locked” to the phase of the transmitter near field. In such ascenario, phase-locking may prevent the overall electrical length of therepeaters from approaching one-quarter of the resonant wavelength. Sucha configuration of repeaters may be referred to as a “phase locked”array of repeaters.

However, shifting the phase of fields in a system may increase theoverall reactive power in the system. The increase in the reactive powerin the system may result in an increase of power losses in the system.Accordingly, in some embodiments, each repeater may be configured toadjust the phase of each repeated field by a determined amount such thatthe reactive power is reduced, while keeping the overall electricallength of repeaters in an array shorter than one-quarter of the resonantwavelength. As such some repeaters need not be configured to shift thephase of their respective repeated field to avoid increasing the overallreactive power in the system. In some examples, the controller of asystem may adjust the phase shifting elements of one or more repeatersin order to adjust the reactive power in the system. This adjustment ofreactive power in a system may be viewed as similar or analogous to apower factor correction, which may occur in conventional powertransmission systems.

FIG. 13 is a conceptual illustration of a relationship between a chainof repeaters and the phases of the respectively repeated near field ateach repeater, according to an exemplary embodiment. By way of example,a transmitter and a chain of five repeaters (labeled Repeater 1-5) areshown. For purposes of illustration, one full wavelength 1300 of a nearfield transmitted by transmitter as the resonant frequency of the systemis shown. Also by way of example, the repeaters are placed at incrementsof 0.1 wavelength from the transmitter, so that the last repeater in thechain as at one quarter wavelength from the transmitter. Wave 1300 isnot representative of the amplitude of the transmitter field, as thetransmitter field decays with distance. Rather, wave 1300 is meant toillustrate a wavelength of the transmitter field oscillating at theresonant frequency of the system.

FIG. 13A illustrates a resonant transmitter near field, which isrepeated by the repeaters 1-5 for the example case that includes nophase adjustment at the repeaters. As illustrated in magnified image1302 of FIG. 13A, each repeated field adds to the aggregate near field,and as such, the line representing the wave gets thicker as eachrepeater repeats the field that it couples with. Furthermore, eachrepeated field is phase shifted with respect to the field that precedesit. Thus, the aggregate of the phase shifted fields, at the 5threpeater, approaches one quarter wavelength of the transmitter nearfield. Accordingly, and as explained above, the aggregate of thetransmitter field and each of the repeated fields of repeaters 1-5, maycause the transmitter and the chain of repeaters to behave like aradiating antenna. Thus power may be radiated as an electromagnetic waveinto a far-field region of the transmitter.

FIG. 13B illustrates a resonant transmitter near field, which isrepeated by the repeaters 1-5 for the example case that now includesphase adjustment at the repeaters. As illustrated in FIG. 13B, the phaseof each repeated field is phase shifted, by its respective repeater, tomatch the phase of the transmitter near field. This may be an example ofa “phase locked” array of repeaters described above. More significantly,and as illustrated in magnified image 1304 of FIG. 13B, the aggregate ofthe phase shifted fields does not combine into a quarter wavelength ofthe transmitter near field. Thus, the transmitter and repeaters 1-5 maynot behave like a radiating antenna. Accordingly, far field radiationmay be suppressed or eliminated.

Furthermore, both the passive and active repeaters may include sidechannel communication interfaces, described above, in order tocommunicate with other components of the system, such as thetransmitter, the receiver(s), and the repeaters. For example, an activerepeater may receive instructions from a controller of the system, whichmay be located in the transmitter, to “inject” a specific amount ofpower into its repeated field. In an example, the controller may makethe determination for an active repeater to inject power based oninformation received from a receiver at the end of a repeater chain thatincludes the active repeater.

Furthermore, an array of repeaters configured to control the phase of afield may behave as a sort of collective metamaterial. As explainedabove, a metamaterial is a material that may have properties that arenot found in nature. As the array of repeaters may control the phaseshift in a way that is different from the natural phase shift thatoccurs while repeating and/or propagating a field, the array ofrepeaters may be considered as a collective metamaterial. Such an arrayof repeaters may be described as a metamaterial configured to suppressfar field radiation by controlling the phase of the field with which themetamaterial couples.

Accordingly, a chain or an array of repeaters configured to control thephase of a near field may be modeled as a single metamaterialelement/unit. For example, the single metamaterial unit may couple witha transmitter near field at one end. On the other end, a receiver maycouple with the phase shifted near field that is repeated by the singlemetamaterial. The phase shift of the repeated field may be the aggregateof the phase shifts of the individual repeaters that make up themetamaterial. In another example, the metamaterial may be a“phase-locked” metamaterial, such that the phase of the near field thatit repeats is identical to, or nearly identical to, a phase of the nearfield of the transmitter.

FIG. 14 illustrates a flowchart showing a method 1400 that may adjustthe phase of a signal from a transmitter near field as it is repeated byone or more repeaters of a system, according to an exemplary embodiment.In some embodiments, method 1400 may be carried out by a controller of asystem.

As shown by block 1402, of FIG. 14, method 1400 may involve causing apower source coupled to a transmitter to provide a signal at anoscillation frequency. The oscillation frequency may be one of the oneor more resonant frequencies of the transmit-resonator of thetransmitter. As shown by block 1404, method 1400 further includescausing the transmitter, in response to the signal from the source, toemit a transmitter signal associated with a transmitter near fieldregion. Accordingly, as shown by block 1406, the method further includescausing at least one of the one or more repeaters to receive arespective first signal associated with a respective first near fieldregion. Furthermore, the method includes causing each of the one or morerepeaters to shift a phase of the respective first signal by a specifiedamount. The respective first near field region of each repeater may bethe transmitter near field, or may be a near field that had beenrepeated by a prior repeater.

The method 1400 may cause at least one of the one or more repeaters toemit a respective second signal associated with a second respective nearfield region, as shown by block 1410. An extent of the second respectivenear field region may be configured to be farther away from thetransmitter than the first respective near field. Block 1412 may includecausing at least one of one or more receivers to couple to at least oneof the at least one final repeater. Accordingly, a wireless resonantcoupling link may be established between the each of the one or morereceivers and at least one of the at least one final repeater. As such,block 1414 may include causing the transmitter to transmit electricalpower to each of the one or more loads via at least one of the one ormore repeaters and the at least one of the one or more receivers.

E. Dynamic Wireless Power Distribution System Probe

Resonant wireless power transfer can be viewed as power transmission viaone or more wireless transmission “paths” or “links.” In addition togenerating an oscillating field for wireless power transmission asdescribed herein, the transmitter may also emit a “probe” signal inorder to ascertain various properties of the wireless power transmission“paths” and entities that interact with the power transferred via thepaths (e.g., receivers, repeaters, etc.). Such a probe can be used as atool for dynamic diagnosis and analysis of electrical “circuit”properties of a wireless power distribution system.

Thus, in accordance with example embodiments, a transmitter may includea signal generator, or the like, configured to transmit one or moretypes of wireless signals in order to determine one or moreelectromagnetic properties of propagation paths in the region in whichwireless power transfer may occur, and to further help distinguishand/or disambiguate between legitimate receivers and possibleunauthorized devices and/or parasitic loads. More specifically, thesignal generator may generate test signals that span a broad frequencyrange to provide a frequency sweep, in a manner like that of a vectornetwork analyzer (VNA) frequency sweep. By analyzing phase and amplitudeinformation of transmitted signals and their reflections, thetransmitter may thus determine electrical properties of a reflectingentity, as well as of the transmission path between the transmitter andthe reflecting entity.

In further accordance with example embodiments, the transmitter mayinclude a test-signal receiver component configured to receive andmeasure reflections of transmitted test signals. A controller associatedwith the transmitter may then determine one or more electromagneticproperties of a reflecting entity by comparing the transmitted testsignals with their corresponding reflections. By analyzing reflectionsof transmitted test signals, electromagnetic properties of variouspropagation paths, including the presence of, and electrical distancesto, reflecting entities, and electromagnetic properties of thosereflecting entities, may be ascertained. In practice, electricaldistance can be measured in terms phase shift or delay of a reflectedsignal with respect to a transmitted (reference) signal. With thisinformation, power delivery to legitimate devices can be optimized, andillegitimate power consumption can be identified and suppressed.Measurements and analyses can be carried out continuously, periodically,or episodically.

Test signals can carry both amplitude and phase information. In furtheraccordance with example embodiments, both types of information can beanalyzed to determine properties of a reflecting entity and of thepropagation path between the transmitter and the reflecting entity. Inan example application, test signals may be generated as continuouswaves of one or more frequencies, such one or more continuous sinusoids.In particular, by varying the frequency of a sinusoid (or other form orcontinuous wave) with time, either continuously or in a stepwisefashion, a test signal can be generated that sweeps across frequencies.For a typical application, the frequency may be varied linearly withtime such that the frequency sweep resembles a ramp (or staircase) infrequency with time. Such a sweep can be repeated from time to time, forexample. The reflections of a sweep signal can be measured by thetest-signal receiver and analyzed in a manner similar to a frequencysweep carried out with vector network analyzer. For example, thereflected sweep signal may display frequency-dependent phase delayscorresponding to electrical distance to a reflecting entity, as wellphase delays resulting from frequency-dependent interactions with thereflecting entity

In an alternative example application, test signals can be time-pulsemodulated. With this arrangement, reflections may correspond toindividually reflected pulses. Again, reflected signals may be measuredby the test-signal receiver. Measurement of pulsed signals and theirreflections may be used for time-of-flight analyses and/or other rangingtechniques. Single frequency continuous wave test signals, frequencysweep test signals, and pulsed test signals are non-limiting examples ofthe types of test signals that can be used to probe electricalproperties of a wireless power transmission region of a transmitter

Electromagnetic properties determined by analysis of test signals andtheir reflections can include impedance and admittance, for example.Reflecting entities can include receivers (both legitimate andunauthorized), repeaters, parasitic loads, and other that can interactelectrically with an electric and/or magnetic field. In an exampleembodiment, an analysis of phase and amplitude information from testpulses and their respective reflections may be used to determineelectrical “locations” of sources of impedance. For example,frequency-dependent characteristics of reflections and measured phasedelays can be used to map out electrical properties along a propagationpath. This can be viewed as analogous to how a VNA may locate stubs,taps, or shorts along a transmission path. In the context of wirelesspower delivery via an oscillating field, test signals can provide a sortof virtual “circuit diagram” of entities as mapped out in the wirelesspower delivery region.

In accordance with example embodiments, the virtual circuit diagramprovided by a frequency sweep can be used in the virtual circuit modelof the system to enhance the accuracy of the model and to help identifylegitimate receivers. As an example, by virtue of detected reflections,repeaters may appear as “hops” along propagation paths. Phase delays canthen be used to ascertain locations of repeaters in terms of electricaldistances to discontinuities in path impedances, for example. In anexample embodiment, mapping the system with one or more frequency sweepscan be carried out as part of the system initialization and repeatedfrom time to time to update the map. The initial map can then be used toassociate circuit locations with respective receivers as they make theirpresence known (e.g., authenticating, requesting power, etc.).

In an example system, analysis of phase delay and amplitude from afrequency sweep can be used to measure the impedance and couplingconstant of a receiver. This information can also be input to a virtualcircuit model of the system to improve the accuracy of the deducedcoupling constant at the operational resonant frequency of powertransfer, and thereby further optimize power transfer.

In further accordance with example embodiments, a frequency sweep testsignal and its reflection from a receiver can be used to determine anumber of repeater hops to the receiver. This can in turn be used todistinguish between a legitimate receiver known to be a certain numberof receiver hops away from the transmitter and an otherwise apparentlysimilar unauthorized receiver determined to be a different number ofhops away. For example, if analysis of a frequency sweep indicates thepresence of more than one receiver having the same (or nearly the same)impedance, these receivers may still be disambiguated by the respectivenumber of repeater hops to each respective receiver, as also determinedfrom analysis of test signals and reflections. A receiver determined tobe at an unrecognized number of hops away can thus be considered anunauthorized receiver, in which case the transmitter may take actions toprevent power transfer, as described above.

In accordance with example embodiments, the controller of thetransmitter can carry out the analysis of transmitted and reflected testsignals, including continuous wave signals, frequency sweep signals, andtime-pulse modulated signals, among others. In particular, thecontroller can control a signal generator to cause a specified type oftest signal or signals. The controller can also control a test-signalreceiver configured to detect one or more reflections and correlate themwith corresponding transmitted test signals. The controller can alsoperform one or more analyses of the transmitted and reflected signals todetermine the various properties and results described above.

Within examples, the controller may use test signals described herein tooptimize or otherwise adjust wireless power transfer as elements areadded to or removed from the system. In some embodiments, a system mayincorporate portable and/or non-stationary repeaters to extend the rangeof a transmitter. For example, a portable repeater may be added into thesystem in order to increase the range of a transmitter in a specificdirection. After an authentication process described herein, thecontroller may probe the environment of the system using a frequencysweep or other form of test signal in order to determine one or moreelectromagnetic properties of the added propagation path.

Furthermore, as explained above, a repeater may include phase elements,which may be adjustable. After determining the properties of thepropagation path that may include the repeater, the controller mayaccordingly send instructions to the repeater that direct its operation.Within examples, the controller may adjust the phase adjusting elementsof the repeater. In other examples, if the repeater is an activerepeater, the controller may also determine the amount of power that therepeater may want to inject into its repeated field.

Operations relating to use test signals described above may beimplemented as a method by one or more processors of a transmitter. Inparticular, the transmitter can include a transmit-resonator that isconfigured to couple power from a power source into an oscillating fieldgenerated by the transmit-resonator resonating at a resonant frequency.As discussed above, the oscillating field can be an oscillating electricfield, an oscillating magnetic field, or both. An example method 1600 isillustrated in the form of a flowchart in FIG. 16.

At step 1602, a signal generator of the transmitter transmits one ormore electromagnetic test signals at one or more frequencies. Inaccordance with example embodiments, the transmitted test signals willcarry both phase and amplitude information.

At step 1604, a test-signal receiver of the transmitter receives areflection of any given one of the transmitted test signals from one ormore reflecting entities. By way of example, a reflecting entity couldbe a repeater or a receiver. Like the given transmitted test signal, thereflection will carry both phase and amplitude information.

At step 1606, a processor of the transmitter determines one or moreelectromagnetic properties of a reflecting entity based on an analysisthe given transmitted test signal and a corresponding reflection. Inparticular, phase and amplitude information of the given transmittedtest signal and its corresponding reflection can be analyzed in a systemof equations to determine such properties as impedance of the reflectingentity and/or characteristic impedance of a propagation path followed bythe given transmitted test signal and its reflection.

It should be understood that steps or blocks of method 1600 as describedherein are for purposes of example only. As such, those skilled in theart will appreciate that other arrangements and other elements (e.g.machines, interfaces, functions, orders, and groupings of functions,etc.) can be used instead, and some elements may be omitted altogetheraccording to the desired results. Further, many of the elements that aredescribed are functional entities that may be implemented as discrete ordistributed components or in conjunction with other components, in anysuitable combination and location.

F. Example Applications

The example wireless power delivery systems described herein may beoperable to provide power to the any number of devices, systems, and/orelements of an “Internet of Things.” The Internet of Things may includeany number or combination of devices in a variety of configurationsand/or arrangements. In particular, one or more transmitters andoptionally one or more repeaters may be spatially organized to provideresonant oscillating fields within a given region, zone, area, volume,or other spatial bound. Other devices acting as receivers may eachinclude receive-resonators so that they may be operably coupled to theseresonant oscillating fields when located within the spatial bound. Insuch a scenario, each device may operably receive power via the resonantoscillating fields and may provide the power to one or more loads.

An example implementation may provide a household wireless powerdelivery system. For example, appliances and other electrically-poweredhousehold devices may be configured to receive power from transmittersand repeaters located throughout the household.

In such a scenario, the wireless power delivery system may increase theconvenience of using electrically-powered devices. As an example, theuse of the devices need not be limited to locations in the householdnear where wired power is accessible (e.g., wall outlets). In addition,the household may be dynamically reconfigured because devices withdifferent functions can be easily relocated in the household spacewithout requiring new wired power connections.

In some embodiments, a greater number of electrically-powered devicesmay be powered in the household at least because delivery of wirelesspower need not depend on a fixed number of physical connections to walloutlets, power strips, or extension cords. Rather, the wireless powerdelivery system may be configured to provide power to a large number ofdevices (e.g. hundreds or thousands of devices, or more). Furthermore,the wireless power delivery system may be configured to more-easilyaccommodate upgrades. In contrast to adding wall outlets and installingelectrical conduit in the household, an upgrade to a wireless powerdelivery system may include an-over-the-air software update. In such ascenario, the software update may enable the wireless power deliverysystem to provide wireless power to a larger number of devices byimproved time-domain multiplexing. Other upgrade types, functions,and/or purposes are possible.

Wireless power delivery systems contemplated herein may provideincreased household automation without extensive wiring. For instance,the household wireless power delivery system may provide power to asystem of automated windows, window treatments, doors, and/or locks.Also, the household wireless power delivery system may be configured toaccommodate room thermostats and other environmental monitoring devicesin each room. Additionally, the household wireless power delivery systemmay be operable to extend to exterior areas. For example, wireless powerdelivery to exterior areas may include providing electrical power toautomated garden sprinklers, outdoor lighting, outdoor cameras, securitydevices, and/or motion, heat, or other sensors. Furthermore, thehousehold wireless power delivery system may allow controls (e.g.,control panels for automated devices) to be flexibly and/or moveablylocated conveniently throughout the household.

As described above, example wireless power delivery systems may beconfigured to detect and identify various receivers within a localproximity. For example, the household wireless power delivery system maybe configured to locate household items that are resonantly coupled toit. Furthermore, the ability to locate household items need not belimited to electrically-powered devices that receive power from thewireless power delivery system. Non-electrically-powered devices, suchas keys, tools, utensils, and clothing, may also be located if, forexample, such objects may include a characteristic tag that may beidentifiable by the wireless power delivery system. For instance, theobjects may incorporate an RFID tag, may have a characteristic RFimpedance, or may include a receive-resonator as described elsewhereherein. Other types of tags or location devices may be incorporated intoobjects so as to find them via the wireless power delivery system.

In contrast to battery-powered devices, the household wireless powerdelivery system may provide continuous power to a device without needfor a battery or another type of energy-storage device. For instance, arobotic vacuum cleaning device receiving wireless power may movecontinuously within the household space without need for replacement orrecharging of batteries.

In another example implementation, a hospital wireless power deliverysystem is contemplated. Electrically-powered medical devices may beconfigured to receive power from transmitters and/or repeaters locatedthroughout the hospital. The hospital wireless power delivery system mayprovide advantages that are similar to the household wireless powerdelivery system above. For instance, medical equipment and other devicescan be easily and conveniently moved within the hospital without needfor new wired power connections. Additionally, the wireless powerdelivery system may be employed to locate hospital items that arecoupled to the resonant oscillating fields of the wireless powerdelivery system. In particular, surgical items may include a tag with areceive-resonator and/or a characteristic impedance detectable by thewireless power delivery system. In such a scenario, locating surgicalitems may help ensure nothing is inadvertently left in a surgical sitebefore closing the body cavity.

Currently, the use of portable electronic devices, such as phones,computer tablets, computer laptops, and watches, may be limited by theextent of their rechargeable battery power or access to a fixed walloutlet. Furthermore, the recharging process often requires a powerconnector to be attached to, and detached from, the portable electronicdevices. Repeated use of the power connector may lead to wear and tearand cause damage to the portable electronic devices.

Some portable electronic devices may employ conventional wireless powerdelivery systems. As described above, however, the coupling factor k insuch conventional systems must be maintained at a sufficiently highlevel in order to establish efficient power transfer. In other words,the portable electronic devices must be to be located in close proximityto, and precisely positioned relative to, the transmitter. Inconventional wireless power delivery systems, the transmitter musttypically have access to a fixed wall outlet. As such, compared to wiredrecharging which also requires access to a fixed wall outlet,conventional wireless power delivery systems merely eliminate the needto physically attach a power connector to the portable electronic deviceand provide no additional positional freedom for the use of the portableelectronic devices.

Thus, in yet another example implementation, wireless power deliverysystems may be employed in common spaces, such as airports, cars,planes, trains, buses, etc., to conveniently allow portable electronicdevices to be recharged and/or powered wirelessly. The portableelectronic devices may include receive-resonators that can be coupled tothe wireless power delivery system. In some cases, the rechargingprocess may occur automatically without user action when a portableelectronic device enters one of these common spaces. That is, theportable electronic device may automatically couple to wireless powerdelivery systems in proximity to the device. In other cases, a portableelectronic device may need to be registered via a wireless power accountand/or may need to be authenticated prior to receiving power from thewireless power delivery system. In some scenarios, the wireless poweraccount may be a paid account that may be associated with a wirelesscommunication network that may provide cellular (e.g. voicecommunication) and/or data services for the portable electronic device.

In a further example implementation, aspects of the present disclosuremay be employed to wirelessly assemble modular computer components. Asshown in FIG. 15, a computer system 1500 includes a plurality of modularcomputer components, which may include a computer processing unit/mainlogic board (CPU/MLB) 1502 a, a graphics processing unit (GPU) 1502 b,one or more hard disks (HD) 1502 c, a secondary optical read/write (R/W)device 1502 d, and a wide area network (WAN) card 1502 e. In otherembodiments, the computer system 1500 may include other/additionalcomputer components.

The GPU 1502 b, the HD 1502 c, the R/W device 1502 d, and the networkcard 1502 e may be communicatively coupled to the CPU/MLB 1502 a. Byexchanging data and other signals with the computer components 1502 b-e,the CPU/MLB 1502 a can centrally control the computer components 1502b-e. To establish such communications, the components 1502 a-e mayinclude respective wireless communication interfaces 1504 a-e as shownin FIG. 15. For instance, the wireless communication interfaces 1504 a-emay establish radio frequency (RF) communications (e.g., 60 Ghz RF)and/or optical freespace communications between the computer components1502 a-e.

The computer system 1500 also includes a wireless power delivery systemto provide the components 1502 a-e with power. In particular, one ormore transmitters 1510 (and optionally one or more repeaters) arespatially organized to provide resonant oscillating fields within adefined spatial bound 1501. The spatial bound 1501, for instance, maycorrespond to the interior space of a hard case for a computerdesktop/tower. Each transmitter 1510 may be coupled to a power source1520 and may include a transmit-resonator 1516 to generate the resonantoscillating fields. The computer components 1502 a-e may each include arespective receive-resonator 1506 a-e configured to be coupled to theresonant oscillating field(s). When located within the spatial bound1501, each computer component 1502 a-e can receive power via theresonant oscillating field(s) to perform its respective function. Insome embodiments, the transmitter(s) 1510 may be integrated with theCPU/MLB 1502 a to centralize control of the computer system 1500further.

By establishing wireless communications and receiving wireless power,the computer components 1502 a-e within the spatial bound 1501 canfunction together as a computer. Advantageously, the wirelessconfiguration of the computer system 1500 eliminates the need for acomplex system of hardwired connections, e.g., wiring harnesses, toconnect the computer components 1502 a-e. Additionally, the wirelessconfiguration facilitates installation and removal of the computercomponents 1502 a-e, e.g., from a computer hard case. As such, thecomputer components 1502 a-e can be easily maintained, repaired, and/orreplaced. The computer system 1500 can also be upgraded just by placingadditional computer components, such as additional hard disks 1502 c, inthe spatial bound 1501 without setting up any hardwired connections. Insome embodiments, the CPU/MLB 1502 a may detect the presence of newcomputer components via the wireless communications and thus incorporatethe new computer components in the operation of the computer system1500.

As described above, the wireless power delivery system may employside-channel communications to coordinate aspects of the power transfer.As such, each transmitter 1510 may also include a wireless communicationinterface 1514 to communicate with each of the computer components 1502a-e acting as receivers. In other words, the communication interfaces1504 a-e may also be employed to provide side-channel communicationswith the transmitter(s) 1510.

As the computer system 1500 demonstrates, a system of components can beassembled according to a modular approach by employing a wireless powerdelivery system as well as wireless communications. Thus, in yet anotherexample implementation, a computer data center may employ a system oftransmitters and repeaters to allow computer servers to be implementedas modular components. The servers can receive power as long as they arelocated within the computer data center. In addition, wirelesscommunications, e.g., freespace optical communications, may be employedto allow data exchange between the servers. The wireless power deliverysystem and the wireless communications allow the servers to be easilydeployed in the computer data center without setting up wired power andwired network connections. The servers can be easily maintained,repaired, and/or replaced. Additionally, the servers can be spatiallyorganized in the computer data center with greater freedom. Although thetransmitters may receive wired power, the servers are not limited tolocations where wired power and/or wired network connections areaccessible.

Because the computer data center uses less wired power and fewer wirednetwork connections, the physical design of the computer data center canplace greater emphasis on other design considerations or features. Forinstance, the physical design can provide more optimal thermalmanagement. Alternatively, the physical design may focus on loweringcosts for building or implementing the computer data center.

III. Wireless Solar Power Delivery

Wireless power delivery systems contemplated herein may be configured towirelessly deliver power derived from an alternative energy source, suchas solar energy for instance. Generally, a solar panel is designed toabsorb the sun's rays as a source of energy for generating electricity.When installing a solar panel, the solar panel may be connected tovarious wires that are used to transmit the generated electricity tovarious loads. Such wiring may be relatively costly, may require custominstallation, and may increase the complexity of installing a solarpanel, thereby increasing the costs of electrical and/or mechanicalinstallation work. Accordingly, disclosed herein are example systemsthat may help to reduce the extent and/or complexity of wiring involvedin the installation of a solar panel.

A. First Example Arrangement

In a first example arrangement, a solar panel system disclosed hereinmay be a stand-alone system that is capable of harnessing solar energyand then wirelessly transmitting generated electricity to a receiver. Inthis way, an individual may simply position this solar panel system at adesired exterior location (e.g., a roof or a window). The solar panelsystem may then wirelessly provide power directly to various loads.Alternatively, the individual may arrange a wireless power receiver(perhaps at an interior location) to receive and distribute among thevarious loads power that is originally generated by the solar panelsystem.

FIG. 17 illustrates an example configuration of a solar panel system1700 disclosed herein. In particular, the solar panel system 1700 isshown to include solar cell(s) 1702, an inverter 1704, an impedancematching network 1706, a bi-directional RF coupler 1708, a side-channelwireless communication interface 1710, a back-channel communicationinterface 1712, a transmit-resonator 1714, and a controller 1716. Notethat the solar panel system 1700 is shown for illustration purposes onlyand solar panel system 1700 may include additional components and/orhave one or more components removed without departing from the scope ofthe disclosure. Further, note that the various components of solar panelsystem 1700 may be arranged and connected in any manner.

Moreover, the above description of an impedance matching network, abi-directional RF coupler, a side-channel wireless communicationinterface, a transmit-resonator, and a controller may apply to anydiscussion below relating to the respective component being used inanother system or arrangements. For instance, as noted, FIG. 10 (amongother possible figures) illustrates a controller 1024, an impedancematching network 1026, a bi-directional RF coupler 1030, a side-channelwireless communication interface 1028, and a transmit-resonator 1022 asbeing incorporated in another arrangement. These components at issue maythus take on the same or similar characteristics (and/or form) as therespective components discussed above in association with FIG. 10.However, the components at issue could also take on othercharacteristics (and/or form) without departing from the scope of thedisclosure.

As noted, the solar panel system 1700 is shown to include solar cell(s)1702, which may also be referred to as photovoltaic cells, among otherpossibilities. By way of example, the solar cell(s) 1702 may be anycurrently existing solar cell(s) or any solar cell(s) developed in thefuture. Regardless, these solar cell(s) 1702 may be configured toconvert solar energy to electrical energy. To do so, the solar cells(s)1702 may apply the photovoltaic effect, which involves the generation ofvoltage or electric current in a material upon exposure to light.Further, the solar cell(s) 1702 may be in an integrated group and may beorientated in a single plane, so as to result in a solar photovoltaicpanel or solar photovoltaic module for instance. Moreover, the solarcell(s) 1702 may be connected in series to create additive voltageand/or may be connected in parallel to yield higher currents, amongother combinations.

Additionally, as noted, the solar panel system 1700 is shown to includeat least one inverter 1704 (could also be referred to as an “oscillator”or a “power oscillator”). By way of example, the inverter 1704 may beany currently exiting power inverter or any power inverter developed inthe future. Regardless, the inverter 1704 may be any device or circuitryarranged to convert direct current (DC) to alternating current (AC). Inan example implementation, this inverter 1704 may be coupled to thesolar cell(s) 1702 and may be configured to receive the electricalenergy generated by the solar cell(s) 1702 (e.g., in the form of DC).The inverter 1704 may then also be configured to convert this electricalenergy to an electrical signal having an oscillation frequency (e.g.,taking the form of AC). In an example implementation, this electricalsignal may have a high oscillation frequency (e.g., 10 MHz). Further,this electrical signal may also have a certain amplitude and/or may beprovided for certain duration, among other possible features. Suchfeatures may be preconfigured or may be configured based onconsiderations further discussed below.

Moreover, the inverter 1704 may also be coupled to thetransmit-resonator 1714 and may provide the transmit-resonator 1714 withthe electrical signal having the oscillation frequency. As noted, theoscillation frequency may be a frequency within a range of resonantfrequencies of the transmit-resonator. Accordingly, once thetransmit-resonator 1714 receives this electrical signal from theinverter 1704, the transmit-resonator 1714 may then resonate at theoscillation frequency. As such, the oscillating transmit-resonator maygenerate a field oscillating at the oscillation frequency. Optionally,an AC to DC converter could be coupled to a receive-resonator thatreceives AC power via the field. This converter may then convert the ACpower to DC power that can then be provided to the load.

Further, as noted, the solar panel system 1700 is shown to include aback-channel communication interface 1712. This back-channelcommunication interface 1712 may provide the solar panel system 1700with an ability to communicate with other entities, such as othersimilar solar panel systems, other wireless power delivery systems,and/or any wired power delivery systems, among others. Accordingly, theback-channel communication interface 1712 may provide for wired and/orwireless communications. In case of wired communications, thesecommunications may occur by way of eight positions/eight conductors(8P8C) connectors, D-subminiature connectors, and/or Universal SerialBus (USB) connectors, among other examples. Whereas, in the case ofwireless communications, these communications may occur by way ofwireless communication links, such as Bluetooth, IEEE 802.11, a widearea wireless link (e.g., cellular) or other wireless basedcommunication links. Other examples are possible as well. Note that theback-channel communication interface 1712 and the side-channel wirelesscommunication interface 1710 may be of the same interface and may thusshare a communication medium (and may transmit on the same or ondifferent channel(s)). Alternatively, the back-channel communicationinterface 1712 may be separate from the side-channel wirelesscommunication interface 1710 (and may transmit on the same or ondifferent channel(s)).

According to example implementations, the disclosed solar panel system1700 may wirelessly transmit power to loads in various ways. Forexample, as noted, a receiver may receive power from the solar panelsystem 1700 and may distribute the power among various loads, such asvia wired connections. FIG. 18 illustrates an example of such animplementation. In particular, FIG. 18 shows three solar panel systems1700A to 1700C each taking the form of a solar panel system 1700described herein. As shown, these solar panel systems 1700A to 1700C maybe connected to each other by way of a back-channel 1802, so as tofacilitate communications between the solar panel systems 1700A to1700C.

Moreover, FIG. 18 also shows an example receive-resonator 1806 (may alsobe referred to or otherwise incorporated within a receiver), which maytake the form the form of receive-resonator 112 described above, forinstance. As shown, the receive-resonator 1806 is operable to be coupledvia wireless resonant coupling links 1804A to 1804C respectively to eachof the solar panel systems 1700A to 1700C (i.e., to the respectivetransmit-resonators of the solar panel systems 1700A to 1700C).Additionally, the receive-resonator 1806 may also be configured toresonate at the above-mention oscillation frequency (among otherfrequencies), so as to result in wireless transmission of power asdiscussed above. Further, the receive-resonator 1806 may be connected toone or more load(s) 1810 via one or more wired connections 1808 and maythus provide such load(s) 1810 with electrical power that thereceive-resonator 1806 receives from the solar panel systems 1700A to1700C via the respective wireless resonant coupling links 1804A to1804C.

FIG. 19 next illustrates how this example implementation may beincorporated within an example house 1900. As shown, the solar panelsystems 1700A to 1700C are each arranged on a roof of the house 1900,such as by way of one or more mechanical connections for instance. Also,the receive-resonator 1806 is shown to be positioned in an attic of thehouse 1900. With this implementation, the solar panel systems 1700A to1700C may transmit power to the receive-resonator 1806 via therespective wireless resonant coupling links 1804A to 1804C. And thereceive-resonator 1806 may be connected to a main electrical system (notshown) of the house 1900 through which the receive-resonator 1806 maythen distribute power to various loads. For instance, a mobile device1902, a speaker 1904, and a refrigerator 1906 may each include a powerplug that is plugged into a socket and may thus receive the distributedelectrical power via the respective sockets.

In another example implementation, as noted, a solar panel systemdisclosed herein may wirelessly provide power more directly to variousloads. FIG. 20 illustrates an example of such an implementation. Inparticular, FIG. 20 shows three solar panel systems 1700A to 1700C eachtaking the form of a solar panel system 1700 described herein. As shown,these solar panel systems 1700A to 1700C may be connected to each otherby way of a back-channel 1802, so as to facilitate communicationsbetween the solar panel systems 1700A to 1700C. Additionally, FIG. 20also shows example receive-resonators 2006A to 2006C, which may eachtake the form the form of receive-resonator 112 described above, forinstance. As shown, the receive-resonator 2006A is operable to becoupled via wireless resonant coupling links 2004A to the solar panelsystem 1700A, the receive-resonator 2006B is operable to be coupled viawireless resonant coupling links 2004B to the solar panel system 1700B,and the receive-resonator 2006C is operable to be coupled via wirelessresonant coupling links 2004C the solar panel system 1700C. Further,each of the receive-resonators 2006A to 2006C may also be configured toresonate at an oscillation frequency (e.g., same oscillation frequencyat which a transmit-resonator of a respective solar panel systemresonates), so as to result in wireless transmission of power asdiscussed above.

Moreover, the receive-resonator 2006A may be connected to a load 2008Avia one or more wired connections and may thus provide the load 2008Awith electrical power that the receive-resonator 2006A receives from thesolar panel system 1700A via the respective wireless resonant couplinglink 2004A. Also, the receive-resonator 2006B may be connected to a load2008B via one or more wired connections and may thus provide the load2008B with electrical power that the receive-resonator 2006B receivesfrom the solar panel system 1700B via the respective wireless resonantcoupling link 2004B. Also, the receive-resonator 2006C may be connectedto a load 2008C via one or more wired connections and may thus providethe load 2008C with electrical power that the receive-resonator 2006Creceives from the solar panel system 1700C via the respective wirelessresonant coupling link 2004C.

In some cases (not shown), however, this implementation may also allowfor multiple solar panel systems to provide power to a singlereceive-resonator. For example, the receive-resonator 2006A may providethe load 2008A with electrical power that the receive-resonator 2006Areceives from the solar panel system 1700A via the respective wirelessresonant coupling link 2004A as well as with electrical power that thereceive-resonator 2006A receives from the solar panel system 1700B viaanother wireless resonant coupling link. Other cases are possible aswell.

FIG. 21 next illustrates how this example implementation may beincorporated within the above-mentioned example house 1900. As shown,the solar panel systems 1700A to 1700C are each arranged on a roof ofthe house 1900, such as by way of one or more mechanical connections forinstance. With this implementation, the solar panel systems 1700A to1700C may transmit power more directly to various devices via therespective wireless resonant coupling links 2004A to 2004C (or perhapsvia one or more repeaters as discussed above). And in this case, suchdevices do not necessarily have to be plugged into a socket. Forexample, the solar panel system 1700A may provide a receive-resonator(not shown) coupled to the refrigerator 1906 with electrical power viathe wireless resonant coupling links 2004A. And this receive-resonatormay then pass this electrical power to the refrigerator 1906. In anotherexample, the solar panel system 1700B may provide a receive-resonator(not shown) coupled to the mobile device 1902 with electrical power viathe wireless resonant coupling links 2004B. And this receive-resonatormay then pass this electrical power to the mobile device 1902. In yetanother example, the solar panel system 1700C may provide areceive-resonator (not shown) coupled to the speaker 1904 withelectrical power via the wireless resonant coupling links 2004C. Andthis receive-resonator may then pass this electrical power to thespeaker 1904. Other examples are possible as well.

B. Second Example Arrangement

In a second example arrangement, a wireless power transmission systemmay be operable to connect to one or more solar panels, such as toexisting solar panels or to solar panels developed in the future, forinstance. With this system, an individual may simply position the solarpanels and the system at a desired location (e.g., a roof) and at arelative vicinity to one another. Once positioned, the individual maysimply wire these solar panels to the system and the system may then beset to receive (e.g., via an inverter) electricity generated by thesolar panels and to then wirelessly provide electrical power usingvarious approaches discussed herein.

FIG. 22 illustrates an example configuration of a wireless powertransmission system 2200 disclosed herein. In particular, the wirelesspower transmission system 2200 is shown to include an impedance matchingnetwork 2206, a bi-directional RF coupler 2208, a side-channel wirelesscommunication interface 2210, a back-channel communication interface2212, a transmit-resonator 2214, and a controller 2216. Note that thewireless power transmission system 2200 is shown for illustrationpurposes only and wireless power transmission system 2200 may includeadditional components and/or have one or more components removed withoutdeparting from the scope of the disclosure. Further, note that thevarious components of wireless power transmission system 2200 may bearranged and connected in any reliable manner. Yet further, the abovedescription of an impedance matching network, a bi-directional RFcoupler, a side-channel wireless communication interface, atransmit-resonator, and a controller may apply to any discussion belowrelating to the respective component being used in another system orarrangements.

Moreover, the wireless power transmission system 2200 is shown asconnected to one or more solar panels(s) 2202. These solar panel(s) 2202may be existing solar panels or may be any solar panels developed in thefuture. In particular, the solar panel(s) 2202 may each include one ormore solar cells, such as the solar cell(s) 1702 discussed above. Inthis arrangement, the wireless power transmission system 2200 mayconnect to one or more solar panels(s) 2202 by way of any connectors,such as power connectors for instance.

Further, the at least one inverter 2204 may take the form of inverter1704 discussed above. In this regard, the inverter 2204 may be coupledto the solar panel(s) 2202 and may be configured to receive electricalenergy generated by the solar panel(s) 2202 (e.g., in the form of DC).The inverter 2204 may then also be configured to convert this electricalenergy to an electrical signal having an oscillation frequency (e.g.,taking the form of AC). As noted, this electrical signal may have a highoscillation frequency (e.g., 10 MHz). Accordingly, the inverter 2204 mayalso be coupled to the transmit-resonator 2214 and may provide thetransmit-resonator 2214 with the electrical signal having theoscillation frequency. And as further noted, the oscillation frequencymay be a frequency within a range of resonant frequencies of thetransmit-resonator. Hence, once the transmit-resonator 2214 receivesthis electrical signal from the inverter 2204, the transmit-resonator2214 may then resonate at the oscillation frequency. As such, theoscillating transmit-resonator may generate a field oscillating at theoscillation frequency.

In some cases, solar panel(s) 2202 may include or may otherwise becoupled to a different inverter (i.e., other than inverter 2204) thatoperates to convert a DC power generated by solar cells of the solarpanel(s) 2202 to AC power (e.g., at 60 Hz). As a result, the wirelesspower transmission system 2200 could receive electrical energy generatedby the solar panel(s) 2202 that is in the form of AC rather than in theform of DC as discussed above. Given such cases, the wireless powertransmission system 2200 may also include a frequency changer (notshown) that operates to convert AC of one frequency (e.g., 60 Hz) to ACof another frequency (e.g., 10 MHz). Additionally or alternatively, thewireless power transmission system 2200 may use the received electricalenergy to operate the inverter 2204 (perhaps using an AC to DC converter(not shown) to generate DC in order to then operate the inverter 2204),which would then generate an electrical signal having a certainoscillation frequency (e.g., 10 MHz). Other approaches are possible aswell.

According to example implementations, the disclosed wireless powertransmission system 2200 may wirelessly transmit power to loads invarious ways. For example, a receiver may receive power from wirelesspower transmission system 2200 and may distribute the power amongvarious loads, such as via wired connections. FIG. 23 illustrates anexample of such an implementation. In particular, FIG. 23 shows twowireless power transmission systems 2200A to 2200B each taking the formof a wireless power transmission system 2200 described herein. As shown,the wireless power transmission system 2200A may receive power from oneor more solar panel(s) 2202A. And the wireless power transmission system2200B may receive power from one or more solar panel(s) 2202B. Also,these wireless power transmission systems 2200A to 2200B may beconnected to each other by way of a back-channel 2302, so as tofacilitate communications between the wireless power transmissionsystems 2200A to 2200B.

Moreover, FIG. 23 also shows an example receive-resonator 2306 (may alsobe referred to or otherwise incorporated within a receiver), which maytake the form of receive-resonator 112 described above, for instance. Asshown, the receive-resonator 2306 is operable to be coupled via wirelessresonant coupling links 2304A to 2304B respectively to each of thewireless power transmission systems 2200A to 2200B (i.e., to therespective transmit-resonators of the wireless power transmissionsystems 2200A to 2200B). Additionally, the receive-resonator 2306 mayalso be configured to resonate at the above-mention oscillationfrequency (among other frequencies), so as to result in wirelesstransmission of power as discussed above. Further, the receive-resonator2306 may be connected to one or more load(s) 2310 via one or more wiredconnections 2308 and may thus provide such load(s) 2310 with electricalpower that the receive-resonator 2306 receives from the wireless powertransmission systems 2200A to 2200B via the respective wireless resonantcoupling links 2304A to 2304B.

FIG. 24 next illustrates how this example implementation may beincorporated within the example house 1900. As shown, the solar panels2202A are each arranged on the roof of the house 1900 and are eachconnected to the wireless power transmission system 2200A. And anothersolar panel 2202B is also arranged on the roof of the house 1900 and isconnected to the wireless power transmission system 2200B. Also, thereceive-resonator 2306 is shown to be positioned in an attic of thehouse 1900. With this implementation, the wireless power transmissionsystems 2200A to 2200B may transmit power to the receive-resonator 2306via the respective wireless resonant coupling links 2304A to 2304B. Andthe receive-resonator 2306 may be connected to a main electrical system(not shown) of the house 1900 through which the receive-resonator 2306may then distribute power to various loads. For instance, a mobiledevice 1902, a speaker 1904, and a refrigerator 1906 may each include apower plug that is plugged into a socket and may thus receive thedistributed electrical power via the respective sockets.

In another example implementation, a wireless power transmission systemdisclosed herein may wirelessly provide power more directly to variousloads. FIG. 25 illustrates an example of such an implementation. Inparticular, FIG. 25 shows two wireless power transmission systems 2200Ato 2200B each taking the form of a wireless power transmission system2200 described herein. As shown, the wireless power transmission system2200A may receive power from one or more solar panel(s) 2202A. And thewireless power transmission system 2200B may receive power from one ormore solar panel(s) 2202B. Also, these wireless power transmissionsystems 2200A to 2200B may be connected to each other by way of aback-channel 2302, so as to facilitate communications between thewireless power transmission systems 2200A to 2200B.

Additionally, FIG. 25 also shows example receive-resonators 2506A to2506B, which may each take the form of receive-resonator 112 describedabove, for instance. As shown, the receive-resonator 2506A is operableto be coupled via wireless resonant coupling links 2504A to the wirelesspower transmission system 2200A while the receive-resonator 2506B isoperable to be coupled via wireless resonant coupling links 2504B to thewireless power transmission system 2200B. Further, each of thereceive-resonators 2006A to 2006C may also be configured to resonate atan oscillation frequency (e.g., same oscillation frequency at which atransmit-resonator of a respective wireless power transmission systemresonates), so as to result in wireless transmission of power asdiscussed above.

Moreover, the receive-resonator 2506A may be connected to a load 2508Avia one or more wired connections and may thus provide the load 2508Awith electrical power that the receive-resonator 2506A receives from thewireless power transmission system 2200A via the respective wirelessresonant coupling link 2504A. Also, the receive-resonator 2506B may beconnected to a load 2508B via one or more wired connections and may thusprovide the load 2508B with electrical power that the receive-resonator2506B receives from the wireless power transmission system 2200B via therespective wireless resonant coupling link 2504B. In some cases (notshown), however, this implementation may also allow for multiplewireless power transmission systems to provide power to a singlereceiver-resonator. For example, the receive-resonator 2506A may providethe load 2508A with electrical power that the receive-resonator 2506Areceives from the wireless power transmission system 2200A via therespective wireless resonant coupling link 2504A as well as withelectrical power that the receive-resonator 2506A receives from thewireless power transmission system 2200B via another wireless resonantcoupling link. Other cases are possible as well.

FIG. 26 next illustrates how this example implementation may beincorporated within the above-mentioned example house 1900. As shown,the solar panels 2202A are each arranged on the roof of the house 1900and are each connected to the wireless power transmission system 2200A.And another solar panel 2202B is also arranged on the roof of the house1900 and is connected to the wireless power transmission system 2200B.With this implementation, the wireless power transmission systems 2200Ato 2200B may transmit power more directly to various devices viawireless resonant coupling links 2600A to 2600C shown in FIG. 26 (orperhaps via one or more repeaters as discussed above). And in this case,such devices do not necessarily have to be plugged into a socket.

For example, the wireless power transmission system 2200A may provide areceive-resonator (not shown) coupled to the refrigerator 1906 withelectrical power via the wireless resonant coupling links 2600A. Andthis receive-resonator may then pass this electrical power to therefrigerator 1906. Additionally, the wireless power transmission system2200A may also provide a receive-resonator (not shown) coupled to themobile device 1902 with electrical power via the wireless resonantcoupling links 2600B. And this receive-resonator may then pass thiselectrical power to the mobile device 1902. In another example, thewireless power transmission system 2200B may provide a receive-resonator(not shown) coupled to the speaker 1904 with electrical power via thewireless resonant coupling links 2600C. And this receive-resonator maythen pass this electrical power to the speaker 1904. Other examples andarrangements are possible as well.

C. Example Operations

Various operations will now be discussed, which may be carried out inthe context of the first arrangement involving the solar panel systemdiscussed above and/or in the context of the second arrangementinvolving the wireless power transmission system discussed above. Forsimplicity, however, these operations will be generally described hereinin the context of the first arrangement discussed above.

In an example implementation, the transmit-resonator 1714 of solar panelsystem 1700 may include at least one transmit inductor, at least onetransmitter common mode capacitor, and/or at least one differential modecapacitor. As such, the controller 1716 of the solar panel system 1700may be configured to perform operations that are the same as (or similarto) those discussed above in the context of method 700, among othermethods described herein. For example, the controller 1716 may determinea mode of operation for the solar panel system 1700. This mode ofoperation may be from among the common mode, differential mode, and/orinductive mode as discussed above. And the controller 1716 may theninstruct the transmit-resonator 1714 of solar panel system 1700 toprovide electrical power according to the determined mode of operation,such as via a wireless resonant coupling link established according tothe determined mode of operation.

In another example implementation, the controller 1716 of the solarpanel system 1700 may be configured to carry out operations to ensurethat supply of power meets power demand of one or more loads. Forinstance, consider a scenario involving at least first and second solarpanel systems wirelessly providing power to various loads. In thisinstance, a first controller of the first solar panel system maydetermine that the second solar panel system provides a first powerlevel to a given load via a respective second wireless resonant couplinglink. This first power level may be defined in terms of watts (W), amongother possibilities. Also, the first controller may determine that thisfirst power level is below a threshold power demand of the given load.In practice, this first power level may end up being below the thresholdpower demand of the given load due to various reasons, such as due tocloud cover for instance (e.g., clouds may at least partially reduce theextent of the sun's rays that reach the solar panel system).

Regardless, the first controller may make these determinations invarious ways. For example, the first controller may receive from asecond controller of the second solar panel system an indication thatthe second solar panel system is providing the given load with a firstpower level and that this first power level is below the threshold powerdemand of the given load (perhaps also identifying the given load in theindication). This indication may be in the form of computer-readabledata packet provided in a form that the first controller can process,among other possibilities. In another example, the first controller mayreceive (e.g., periodically) from the second controller of the secondsolar panel system an indication of a power level that the second solarpanel system provides to the given load. Once the first controllerreceives this indication, the first controller may compare the indicatedpower level to the threshold power demand of the given load, so as todetermine whether the indicated power level is below the threshold powerdemand. In particular, the first controller may determine this thresholdpower demand by receiving this information from the given load via aside-channel or by receiving this information from the second solarpanel system via back-channel, among other possibilities.

Accordingly, if the first controller determines that the indicated powerlevel (i.e., the first power level) is below the threshold power demandof the given load, the first controller may responsively carry outvarious operations to ensure that the threshold power demand of thegiven load is met. More specifically, the first controller may receivedata indicating power transmission characteristics for the secondwireless resonant coupling link through which the second solar panelsystem provides power to the given load. And once the first controllerreceives this data, the first controller may then instruct thetransmit-resonator of the first solar panel system to provide a secondpower level to the given load via a respective first wireless resonantcoupling link and to do so in accordance with the indicated powertransmission characteristics.

In one case, this second power level may meet (be at or above) thethreshold power demand of the given load. In this case, the first solarpanel system may essentially begin providing power to the given loadinstead of the second solar panel system. And in another case, the firstand second power levels may collectively meet (be at or above) thethreshold power demand of the given load. For instance, the thresholdpower demand of the given load may be at sixty watts (60 W) and thefirst power level provided by the second solar panel system may be attwenty watts (20 W). As such, the power level to be provided by thefirst solar panel system may then be at forty watts (40 W) or higher, soas to meet the threshold power demand of 60 W. Moreover, this approachmay extend to two or more solar panel systems each providing a certainpower level and these power levels may then collectively meet thethreshold power demand. Further, in this case, the first and secondsolar panel systems may essentially collaborate to provide the givenload with a power level that meets the threshold power demand of thegiven load. Other cases are possible as well.

Moreover, the indicated power transmission characteristics may bereceived by the first controller in various ways. By way of example,upon determining that that the first power level is below the thresholdpower demand of the given load, the first controller may responsivelytransmit a request to the second panel system via a back-channel or tothe given load via a side-channel, among others. This request mayinclude a request for the data indicating power transmissioncharacteristics for the respective second wireless resonant couplinglink through which the second solar panel system provides power to thegiven load. Other examples are possible as well.

In this example implementation, the data indicating power transmissioncharacteristics may include various characteristics. In one case, thefirst controller may receive data indicating a mode of operation for thesecond wireless resonant coupling link. This mode of operation may bethe common mode, the differential mode, and/or the inductive mode. Inthis case, the first controller may use this received data as a basisfor determining a mode of operation for the first solar panel system. Inparticular, the first controller may determine that the first solarpanel system should establish the first wireless resonant coupling linkto provide power to the given load in accordance with the same mode ofoperation of the second wireless resonant coupling link provided by thesecond solar panel system. As such, the first controller may instruct atransmit resonator of the first solar panel system to provide theabove-mentioned second power level to the given load via the establishedfirst wireless resonant coupling link and in accordance with the mode ofoperation indicated in the receive data.

By way of example, the second solar panel system may provide power tothe given load via the second wireless resonant coupling link and inaccordance with the common mode. In this example, the first solar panelsystem may receive data indicating that the second solar panel systemprovides power to the given load via the second wireless resonantcoupling link in accordance with the common mode. As such, the firstsolar panel system may then establish the first wireless resonantcoupling link in order to provide to the given load electrical power inaccordance with the common mode. Other examples are possible as well.

In another case, the first and second solar panel systems may each beconfigured to provide electrical power that is distributed according tothe TDMA approach discussed above. In this case, the first solar panelsystem may receive data indicating timing with which the second solarpanel system provides the given load with electrical power according tothe TDMA approach. And the first controller of the first solar panelsystem may then instruct the transmit-resonator of the first solar panelsystem to provide the second power level to the given load in accordancewith the indicated timing.

By way of example, the second solar panel system may have establishedthe second wireless resonant coupling link to be shared by a pluralityof loads (e.g., a plurality of receivers each coupled to a load), whichinclude the above-mentioned given load. Moreover, within a given timeframe, the transmit-resonator of the second solar panel system maydistribute power to a load of the plurality of loads during at least onetime slot. For instance, the above-mentioned given load may be assignedto receive power during a fourth time slot (e.g. T4) within the timeframe. As such, the first solar panel system may receive data indicatingthat the given load may be assigned to receive power during the fourthtime slot within the time frame. And the controller of the first solarpanel system may then instruct the transmit-resonator of the first solarpanel system to provide the second power level to the given load duringthis fourth time slot. Other examples are possible as well.

In yet another case, as noted above, each load of the plurality of loadsmay be associated with a respective priority, such that higher priorityloads may receive more power during a single power distribution cyclethan lower priority loads. As such, a controller may generate orotherwise obtain a dynamic priority list. In this case, the first solarpanel system may receive data indicating a priority associated with theabove-mentioned given load. And the first controller of the first solarpanel system may then instruct the transmit-resonator of the first solarpanel system to provide power (e.g., perhaps even higher than the secondpower level) to the given load in accordance with the indicatedpriority.

In yet another case, as noted above, the resonant frequency that thesignal may oscillate at, also called the system resonant frequency, maybe chosen by a controller of a system, such as those systems discussedherein. In this case, the first solar panel system may receive dataindicating a resonant frequency, originally chosen by the secondcontroller, with which the second solar panel system provides power tothe given load. And the first controller of the first solar panel systemmay then instruct the transmit-resonator of the first solar panel systemto provide the second power level to the given load in accordance withthe indicated resonant frequency. Additionally or alternatively, thefirst controller of the first solar panel system may instruct aninverter of the first solar panel system to generate an electricalsignal to have an oscillation frequency that matches the indicatedresonant frequency, so as to ultimately cause the transmit-resonator ofthe first solar panel system to provide the second power level to thegiven load in accordance with the indicated resonant frequency.

In yet another case, the first and second solar panel systems may eachinclude phase adjustment elements (not shown) operable to shift thephase of a signal provided to a respective transmit-resonator. In thiscase, the first solar panel system may receive data indicating a phaseshift applied by the second solar panel system. And the first controllerof the first solar panel system may then instruct phase adjustmentelements of the first solar panel system to apply the indicated phaseshift to a signal provided to the transmit-resonator of the first solarpanel system. Other cases are possible as well.

In yet another example implementation, the first solar panel system mayalso be configured to essentially request assistance from the secondsolar panel system, so as to ensure that the supply of power meets thepower demand of one or more loads. For instance, the first controller ofthe first solar panel system may determine that the first solar panelsystem provides a first power level to a given load via a respectivefirst wireless resonant coupling link. Also, the first controller maydetermine that this first power level is below a threshold power demandof the given load. As such, the first controller of the first solarpanel system may then responsively send to the second solar panel system(e.g., to the respective second controller of the second solar panelsystem) both (i) data indicating power transmission characteristics forthe first wireless resonant coupling link and (ii) an instruction forthe second solar panel system to provide a second power level to thegiven load via a respective second wireless resonant coupling link andin accordance with the indicated power transmission characteristics.

In one case, this second power level may meet (be at or above) thethreshold power demand of the given load. In this case, the second solarpanel system may essentially begin providing power to the given loadinstead of the first solar panel system. And in another case, the firstand second power levels may collectively meet (be at or above) thethreshold power demand of the given load. In this case, the first andsecond solar panel systems may essentially collaborate to provide thegiven load with a power level that meets the threshold power demand ofthe given load. Moreover, this approach may extend to two or more solarpanel systems each providing a certain power level and these powerlevels may then collectively meet the threshold power demand. Othercases are also possible.

In yet another example implementation, the first and second solar panelsystems may each provide power to the given load simultaneously and mayassist one another in the event of reduction in available power that oneof the systems can provide. In particular, the first solar panel systemmay provide a first power level to the given load while the second solarpanel system may provide a second power level to the given load, so asto collectively meet the threshold power demand of the given load. Whiledoing so, the first solar panel system may determine that the secondpower level provided by the second solar panel system has dropped to athird power level that is lower than the second power level (e.g., dueto cloud cover decreasing the power that respective solar cells of thesecond solar panel system can produce), thereby resulting in thecollective provided power being below the threshold power demand.Responsively, the first controller of the first solar panel system mayincrease the first power level to a fourth power level (e.g., cloudcover may not affect the first solar panel system and thus therespective solar cells of the first solar panel system may generatesurplus power), so as to again meet the threshold power demand.

By way of example, the first and second solar panel systems may eachprovide 30 W of power, so as to meet a threshold power demand of thegiven load that is at 60 W. In this example, the first solar panelsystem may determine that the power level provided by the second solarpanel system has dropped to 20 W. Responsively, the first controller ofthe first solar panel system may then increase the power level providedby the first solar panel system to 40 W, so as to again meet thethreshold power demand of the given load. Other examples are possible aswell.

In yet another example implementation, a solar panel system may seekassistance from a different source of power such as in the event that noother solar panel system can provide assistance with supply of powerthat is harvested from solar energy. For instance, the first controllerof the first solar panel system may determine that the first solar panelsystem provides a first power level to a given load via a respectivefirst wireless resonant coupling link. And the first controller maydetermine that this first power level is below a threshold power demandof the given load. Also, the first controller may determine that thesecond solar panel system is also generating insufficient power levels(e.g., due to cloud cover) and thus that no solar panel system (e.g.,positioned near the given load) can provide the given load with a powerlevel that meets the threshold power demand of the given load.Responsively, the first controller may send an instruction to thedifferent source of power to provide power (e.g., at a second powerlevel) to the given load and/or an instruction to the given load toinstead receive power from this different source of power. For example,this different source of power may a wireless power system connected tothe electrical power grid. And in another example, this different sourceof power may be a wireless power system connected to an energy storagedevice (e.g., a battery).

Regardless, this different source of power may be connected to the firstsolar panel system (or to a first wireless power transmission systemwhen carried out in this context), such that the solar panel system candraw power from this different source of power and then wirelesslytransmit the power to the given load. In another case, this differentsource of power may be connected to the second solar panel system. Inthis case, the first solar panel system may instruct the second solarpanel system to (a) receive a second power level from the differentsource of power and (b) provide the second power level to the at leastone load via at least one different wireless resonant coupling link. Asdiscussed, this different wireless resonant coupling link may beestablished according to power transmission characteristics that thefirst solar panel system provides to the second solar panel system. Inyet another case, this different source of power may be connected to areceive-resonator that may pass power drawn from this other source ofpower to the given load. In either of these cases, the second powerlevel provided by the different source of power may meet the thresholdpower demand. Alternatively, the combination of the first and secondpower levels may at least partially meet the threshold power demand.Other cases and examples are possible as well.

In yet another example implementation, a solar panel system may beconfigured to stop wireless transmission of power in response todetermining that no load requires reception power from the solar panelsystem. In particular, solar cells of the solar panel system maygenerate electrical energy as long as these solar cells receive solarenergy. Due to these characteristics of solar cells, the solar panelsystem may thus be configured to adjust power transmission. As such, inone case, the solar panel system may communicate with a load via aside-channel and may determine that a current threshold power demand ofthe load is at zero watts, thereby indicating that the load does notrequire reception of power at that time. In another case, the solarpanel system may determine that no loads are present in the vicinity ofthe solar panel system (e.g., no currently established side-channels forcommunication with loads). In yet another case, the solar panel systemmay determine that at least one load is present in the vicinity of thesolar panel system but may also determine that the another solar panelsystem is already providing sufficient power to the at least one load(e.g., making the determination by way of back-channel communicationwith the other solar panel system and/or by way of side-channelcommunication with the at least one load). In such cases, the solarpanel system may responsively stop wireless transmission of power. Indoing so, the solar panel system may divert the power for storage at anenergy storage device and/or may divert the power to the electricalpower grid, among other possibilities. Other implementations arepossible as well.

In a further aspect, an interface may be provided through which inputmay be received (e.g., from a user) to establish certain preferencesrelated to the systems disclosed herein. This interface may be coupledto a controller of a solar panel system or may be provided on acomputing device that is in communication with the controller of thesolar panel system, among other possibilities. In particular, theinterface may provide for an option to choose the solar panel systemover another source (e.g., the electrical power grid) for providingpower to a selected load. For example, a user may provide input toindicate that a particular mobile device should receive from the solarpanel system (instead of from another source) when such power isavailable. In this manner, the interface provides a user with an abilityto choose a renewable energy source as a preferred source of energy forthe user's various devices.

In yet a further aspect, the various systems disclosed herein may alsobe arranged in the context of other variable power sources, such aspower sources reliant on other forms of renewable energy for instance.These power sources may include (without limitation): wind powersources, hydro power sources, power sources reliant on geothermalenergy, and power sources reliant on bio energy, among otherpossibilities. For example, the wireless power transmission system 2200discussed above may receive power from wind turbine(s) instead of (or inaddition to) the solar panel(s) 2202 shown in FIG. 22. Other examplesand aspects are possible as well.

IV. Conclusion

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for providedfor explanatory purposes and are not intended to be limiting, with thetrue scope being indicated by the following claims.

We claim:
 1. A solar panel system comprising: one or more solar cellsconfigured to convert solar energy to electrical energy; at least oneinverter coupled to the one or more solar cells and configured to (i)receive the electrical energy and (ii) convert the electrical energy toan electrical signal having an oscillation frequency; at least onetransmit resonator coupled to the at least one inverter, wherein the atleast one transmit resonator is configured to resonate at at least theoscillation frequency, and wherein the at least one transmit resonatoris operable to be coupled via at least one wireless resonant couplinglink to at least one receive resonator that is also configured toresonate at at least the oscillation frequency; and a controllerconfigured to: determine for the solar panel system at least one mode ofoperation from among one or more of the following modes: (i) a commonmode and (ii) a differential mode; instruct the at least one transmitresonator to provide via the at least one wireless resonant couplinglink electrical power according to the determined at least one mode ofoperation; determine that a second solar panel system provides a firstpower level to at least one load via at least one different wirelessresonant coupling link; and determine that the first power level isbelow a threshold power demand of the at least one load and responsively(i) receive data indicating power transmission characteristics for theat least one different wireless resonant coupling link and (ii) instructthe at least one transmit resonator to provide via the at least onewireless resonant coupling link a second power level to the at least oneload in accordance with the indicated power transmissioncharacteristics.
 2. The solar panel system of claim 1, wherein the atleast one transmit resonator comprises one or more of the followingcomponents: (i) at least one transmitter common mode capacitor and (ii)at least one transmitter differential mode capacitor, wherein the commonmode provides the at least one wireless resonant coupling link via theat least one transmit common mode capacitor, and wherein thedifferential mode provides the at least one wireless resonant couplinglink via the at least one transmit differential mode capacitor.
 3. Thesolar panel system of claim 1, wherein the at least one receiveresonator is coupled to the at least one load and is configured toprovide, to the at least one load, electrical power that the at leastone receive resonator receives from the at least one transmit resonatorvia the at least one wireless resonant coupling link.
 4. The solar panelsystem of claim 3, wherein the indicated power transmissioncharacteristics are first power transmission characteristics, andwherein the controller is further configured to: determine that a thirdpower level is provided to the at least one load via the at least onewireless resonant coupling link; and determine that the third powerlevel is below the threshold power demand of the at least one load andresponsively send to the second solar panel system both: (i) dataindicating second power transmission characteristics for the at leastone wireless resonant coupling link and (ii) an instruction for thesecond solar panel system to provide a fourth power level to the atleast one load via the at least one different wireless resonant couplinglink in accordance with the second power transmission characteristics.5. The solar panel system of claim 1, wherein the second power levelmeets the threshold power demand of the at least one load.
 6. The solarpanel system of claim 1, wherein a combination of the first and secondpower levels at least partially meets the threshold power demand of theat least one load.
 7. The solar panel system of claim 1, whereinreceiving data indicating power transmission characteristics for the atleast one different wireless resonant coupling link comprises receivingdata indicating at least one mode of operation for the at least onedifferent wireless resonant coupling link, and wherein the at least onemode of operation for the at least one different wireless resonantcoupling link is from among one or more of the following modes: (i) thecommon mode and (ii) the differential mode.
 8. The solar panel system ofclaim 7, wherein determining for the solar panel system the at least onemode of operation is based at least in part on the indicated powertransmission characteristics for the at least one different wirelessresonant coupling link, and wherein instructing the at least onetransmit resonator to provide via the at least one wireless resonantcoupling link electrical power according to the determined at least onemode of operation comprises instructing the at least one transmitresonator to provide via the at least one wireless resonant couplinglink the second power level to the at least one load in accordance withthe indicated at least one mode of operation for the at least onedifferent wireless resonant coupling link.
 9. The solar panel system ofclaim 1, wherein the controller is further configured to instruct the atleast one transmit resonator to provide via the at least one wirelessresonant coupling link electrical power that is distributed over timeaccording to a time division multiple access (TDMA) approach, whereinthe second solar panel system is configured to provide via the at leastone different wireless resonant coupling link electrical power that isdistributed over time according to the TDMA approach, and whereinreceiving data indicating power transmission characteristics for the atleast one different wireless resonant coupling link comprises receivingdata indicating timing with which the second solar panel system providesthe at least one load via the at least one different wireless resonantcoupling link with electrical power according to the TDMA approach. 10.The solar panel system of claim 9, wherein instructing the at least onetransmit resonator to provide via the at least one wireless resonantcoupling link a second power level to the at least one load inaccordance with the indicated power transmission characteristicscomprises: instructing the at least one transmit resonator to providevia the at least one wireless resonant coupling link the second powerlevel to the at least one load in accordance with the indicated timing.11. A wireless power transmission system comprising: at least onetransmit resonator operable to receive at least one electrical signalhaving an oscillation frequency, wherein the at least one electricalsignal is generated from electrical energy that the wireless powertransmission system receives from one or more solar panel systems,wherein the one or more solar panel system are configured to convertsolar energy to electrical energy, wherein the at least one transmitresonator is configured to resonate at at least the oscillationfrequency, wherein the at least one transmit resonator is operable to becoupled via at least one wireless resonant coupling link to at least onereceive resonator that is also configured to resonate at at least theoscillation frequency, and wherein the at least one receive resonator iscoupled to at least one load and is configured to provide, to the atleast one load, electrical power that the at least one receive resonatorreceives from the at least one transmit resonator via the at least onewireless resonant coupling link; and a controller configured to:determine for the wireless power transmission system at least one modeof operation from among one or more of the following modes: (i) a commonmode and (ii) a differential mode; instruct the at least one transmitresonator to provide via the at least one wireless resonant couplinglink electrical power according to the determined at least one mode ofoperation; determine that a first power level is provided to the atleast one load via the at least one wireless resonant coupling link; anddetermine that the first power level is below a threshold power demandof the at least one load and responsively send to a second wirelesspower transmission system both: (i) data indicating power transmissioncharacteristics for the at least one wireless resonant coupling link and(ii) an instruction for the second wireless power transmission system toprovide a second power level to the at least one load via at least onedifferent wireless resonant coupling link established in accordance withthe indicated power transmission characteristics.
 12. The wireless powertransmission system of claim 11, wherein the at least one transmitresonator comprises one or more of the following components: (i) atleast one transmitter common mode capacitor and (ii) at least onetransmitter differential mode capacitor, wherein the common modeprovides the at least one wireless resonant coupling link via the atleast one transmit common mode capacitor, and wherein the differentialmode provides the at least one wireless resonant coupling link via theat least one transmit differential mode capacitor.
 13. The wirelesspower transmission system of claim 11, wherein the indicated powertransmission characteristics are first power transmissioncharacteristics, and wherein the controller is further configured to:determine that the second wireless power transmission system provides athird power level to the at least one load via the at least onedifferent wireless resonant coupling link, wherein the second wirelesspower transmission system comprises at least one different transmitresonator operable to receive, from one or more different solar panelsystems configured to convert solar energy to electrical energy, atleast one electrical signal having the oscillation frequency; anddetermine that the third power level is below the threshold power demandof the at least one load and responsively (i) receive data indicatingsecond power transmission characteristics for the at least one differentwireless resonant coupling link and (ii) instruct the at least onetransmit resonator to provide via the at least one wireless resonantcoupling link a fourth power level to the at least one load inaccordance with the second power transmission characteristics.
 14. Thewireless power transmission system of claim 13, wherein receiving dataindicating second power transmission characteristics for the at leastone different wireless resonant coupling link comprises: receiving dataindicating at least one mode of operation for the at least one differentwireless resonant coupling link, wherein the at least one mode ofoperation for the at least one different wireless resonant coupling linkis from among one or more of the following modes: (i) the common modeand (ii) the differential mode; and receiving data indicating timingwith which the second wireless power transmission system provides the atleast one load via the at least one different wireless resonant couplinglink with electrical power according to a time division multiple access(TDMA) approach.
 15. A method comprising: determining, by a controller,for a wireless power transmission system at least one mode of operationfrom among one or more of the following modes: (i) a common mode and(ii) a differential mode, wherein the wireless power transmission systemcomprises at least one transmit resonator operable to receive at leastone electrical signal having an oscillation frequency, wherein the atleast one electrical signal is generated from electrical energy that thewireless power transmission system receives from one or more solar panelsystems, wherein the one or more solar panel system are configured toconvert solar energy to electrical energy, wherein the at least onetransmit resonator is configured to resonate at at least the oscillationfrequency, and wherein the at least one transmit resonator is operableto be coupled via at least one wireless resonant coupling link to atleast one receive resonator that is also configured to resonate at atleast the oscillation frequency; instructing, by the controller, the atleast one transmit resonator to provide via the at least one wirelessresonant coupling link electrical power according to the determined atleast one mode of operation; determining, by the controller, that afirst power level is provided to at least one load via the at least onewireless resonant coupling link; determining, by the controller, thatthe first power level is below a threshold power demand of the at leastone load; and in response to determining that the first power level isbelow a threshold power demand of the at least one load, the controlleroperating the wireless power transmission system to (i) receive a secondpower level from a different source of power and (ii) provide the secondpower level to the at least one load via the at least one wirelessresonant coupling link.
 16. The method of claim 15, further comprising:determining, by the controller, that a second wireless powertransmission system provides a third power level to the at least oneload via at least one different wireless resonant coupling link, whereinthe second wireless power transmission system comprises at least onedifferent transmit resonator operable to receive, from one or moredifferent solar panel systems configured to convert solar energy toelectrical energy, at least one electrical signal having the oscillationfrequency; and determining, by the controller, that the third powerlevel is below the threshold power demand of the at least one load andresponsively (i) receiving data indicating power transmissioncharacteristics for the at least one different wireless resonantcoupling link and (ii) instructing the at least one transmit resonatorto provide via the at least one wireless resonant coupling link a fourthpower level to the at least one load in accordance with the indicatedpower transmission characteristics.
 17. The method of claim 16, whereinreceiving data indicating power transmission characteristics for the atleast one different wireless resonant coupling link comprises: receivingdata indicating at least one mode of operation for the at least onedifferent wireless resonant coupling link, wherein the at least one modeof operation for the at least one different wireless resonant couplinglink is from among one or more of the following modes: (i) the commonmode and (ii) the differential mode; and receiving data indicatingtiming with which the second wireless power transmission system providesthe at least one load via the at least one different wireless resonantcoupling link with electrical power according to a time divisionmultiple access (TDMA) approach.
 18. The method of claim 15, wherein thedifferent source of power is a first different source of power, themethod further comprising: determining, by the controller, that a thirdpower level is provided to the at least one load via the at least onewireless resonant coupling link; and determining, by the controller,that the third power level is below the threshold power demand of the atleast one load and responsively sending to a second wireless powertransmission system both: (i) data indicating power transmissioncharacteristics for the at least one wireless resonant coupling link and(ii) an instruction for the second wireless power transmission system to(a) receive a fourth power level from a second different source of powerand (b) provide the fourth power level to the at least one load via atleast one different wireless resonant coupling link established inaccordance with the indicated power transmission characteristics.